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Biomedical subjects

L Peng

Publications and source records attributed to L Peng.

At least 37 records · Page 2Linked to original sources
PubMed2001

Automated reticulocyte counting using the Sysmex RAM-1.

Reticulocyte counting using the Sysmex RAM-1 was evaluated. The results of 113 samples analysed on the Sysmex RAM-1 were compared with those from both flow cytometry (FCM) and a manual technique. Reticulocyte counting with the Sysmex RAM-1 showed excellent precision, with an overall coefficient of variance (CV) less than 5%, and almost no carry-over. Reticulocyte counts were stable after blood storage for 48 h at 4 degrees C and room temperature (RT). Linearity was demonstrated very well for Sysmex RAM-1 and FCM (rRAM=0.9998, rFCM=0.9974, P < 0.001) when reticulocyte counts were 5 x 109/l-480 x 109/l. Comparisons of methods showed a good relation for reticulocyte counts between Sysmex RAM-1 and manual counting (r=0.9760), FCM and manual counting (r=0.9623), and Sysmex RAM-1 and FCM (r=0.9527). Analysis of receiver operating characteristic curves showed that the true-positive rate (TPR) was 0.95 for Sysmex RAM-1, and 0.83 for FCM; the area under curve was 0.999 and 0.972 for Sysmex RAM-1, 0.990 and 0.900 for FCM. These findings confirm that Sysmex RAM-1 can make counting reticulocytes easier, more accurate and more reproducible.

Humans↗
PubMed2001

Determination of peripheral blood stem cells by the Sysmex SE-9500.

The Sysmex SE-9500 automated haematology analyser provides an estimate of immature cells, referred to as 'haematopoietic progenitor cells' (HPC). The aim of this study was to evaluate the reliability and usefulness of the SE-9500 HPC parameter as compared with the CD34 + cell count and to determine whether the HPC count was of value in predicting the optimal harvesting time for peripheral blood stem cells (PBSC). Studies were performed on 112 samples from 21 patients with haematological malignancies and 13 healthy donors undergoing progenitor cell mobilisation. Coefficients of variation for the HPC count were 30%, 23.8%, 12.4% and 8.3% respectively for samples with low (4 x 106/l), medium (13 x 106/l), high (250 x 106/l) and very high (2413 x 106/l) counts. There was good linearity for HPC measurement in both peripheral blood (PB) and purified CD34 + cell suspensions (r > 0.995), and no detectable carryover was observed. There was an acceptable correlation between HPC and CD34 + cell counts for PB samples (r=0.669) and for CD34 + cell suspensions (r=0.859). Analysis of purified CD34 + cells using the SE-9500 HPC mode revealed that they appear both in the blast cell area and the immature granulocyte area of the analyser cell display. Quantitation of CD34 + cells and HPC during PBSC mobilisation showed good agreement between these parameters with regard to the optimal time for PBSC harvesting. These findings suggest that HPC counting with the Sysmex SE-9500 may be clinically useful for optimising the timing of PBSC collection.

Antigens, CD34↗
PubMed2001

Laboratory evaluation of the Sysmex SE-9500 automated haematology analyser.

The Sysmex SE-9c500 is a new, fully automated haematology analyser, providing a complete blood count (CBC), including a five-part differential count (DC), with flagging of morphological abnormalities. The SE-9500 was evaluated according to guidelines published by the International Committee for Standardisation in Haematology (ICSH). The results demonstrated minimal carryover (< 0.01%) and excellent linearity for WBC, RBC, HGB and platelet (PLT) (r > 0.995). Samples were stable with regard to CBC parameters after storage for up to 48 h at room temperature (RT) and 4 degrees C. Imprecision was generally acceptable for all CBC parameters (CV < 5%). Correlation between the SE-9500 and reference methods was excellent (r > 0.97) for all the major CBC parameters (WBC, RBC, HGB, PLT). There was minimal interference for WBC, RBC, HGB and PLT at high concentrations of bilirubin (BIL=224 micromol/l) or triglyceride (TG=7.78 mmol/l). SE-9500 reference values for CBC parameters are presented. Our results indicate that the SE-9500 is an excellent tool for routine haematological examination.

Adult↗
PubMed2001

Temperature-sensitive alleles of RSW2 link the KORRIGAN endo-1,4-beta-glucanase to cellulose synthesis and cytokinesis in Arabidopsis.

An 8.5-kb cosmid containing the KORRIGAN gene complements the cellulose-deficient rsw2-1 mutant of Arabidopsis. Three temperature-sensitive alleles of rsw2 show single amino acid mutations in the putative endo-1,4-beta-glucanase encoded by KOR. The F1 from crosses between kor-1 and rsw2 alleles shows a weak, temperature-sensitive root phenotype. The shoots of rsw2-1 seedlings produce less cellulose and accumulate a short chain, readily extractable glucan resembling that reported for rsw1 (which is defective in a putative glycosyltransferase required for cellulose synthesis). The double mutant (rsw2-1 rsw1) shows further reductions in cellulose production relative to both single mutants, constitutively slow root growth, and enhanced temperature-sensitive responses that are typically more severe than in either single mutant. Abnormal cytokinesis and severely reduced birefringent retardation in elongating root cell walls of rsw2 link the enzyme to cellulose production for primary cell walls and probably cell plates. The Rsw2(-) phenotype generally resembles the Kor(-) and cellulose-deficient Rsw1(-) phenotypes, but anther dehiscence is impaired in Rsw2-1(-). The findings link a second putative enzyme activity to cellulose synthesis in primary cell walls of Arabidopsis and further increases the parallels to cellulose synthesis in Agrobacterium tumefaciens where the celA and celC genes are required and encode a putative glycosyltransferase and an endo-1,4-beta-glucanase related to RSW1 and KOR, respectively.

Alleles↗
PubMed2001

The experimental herbicide CGA 325'615 inhibits synthesis of crystalline cellulose and causes accumulation of non-crystalline beta-1,4-glucan associated with CesA protein.

Developing cotton (Gossypium hirsutum) fibers, cultured in vitro with their associated ovules, were used to compare the effects of two herbicides that inhibit cellulose synthesis: 2,6-dichlorobenzonitrile (DCB) and an experimental thiatriazine-based herbicide, CGA 325'615. CGA 325'615 in nanomolar concentrations or DCB in micromolar concentrations causes inhibition of synthesis of crystalline cellulose. Unlike DCB, CGA 325'615 also causes concomitant accumulation of non-crystalline beta-1,4-glucan that can be at least partially solubilized from fiber walls with ammonium oxalate. The unusual solubility of this accumulated glucan may be explained by its strong association with protein. Treatment of the glucan fraction with protease changes its size distribution and leads to precipitation of the glucan. Treatment of the glucan fraction with cellulase digests the glucan and also releases protein that has been characterized as GhCesA-1 and GhCesA-2--proteins that are believed to represent the catalytic subunit of cellulose synthase. The fact that cellulase treatment is required to release this protein indicates an extremely tight association of the glucan with the CesA proteins. In addition, CGA 325'615, but not DCB, also causes accumulation of CesA protein and a membrane-associated cellulase in the membrane fraction of fibers. In addition to the effects of CGA 325'615 on levels of both of these proteins, the level of both also shows coordinate regulation during fiber development, further suggesting they are both important for cellulose synthesis. The accumulation of non-crystalline glucan caused by CGA 325'615 mimics the phenotype of the cellulose-deficient rsw1 mutant of Arabidopsis that also accumulates an apparently similar glucan (T. Arioli, L. Peng, A.S. Betzner, J. Burn, W. Wittke, W. Herth, C. Camilleri, H. Hofte, J. Plazinski, R. Birch et al. [1998] Science 279: 717).

Amino Acid Sequence↗
PubMed2001

A microcalorimetric study of the effect of La3+ on mitochondria isolated from Star-Cross 288 chicken liver tissue cells.

The thermogenic curves of the metabolism of mitochondria isolated from the liver of chicken Star-Cross 288 and the effect of La3+ on it were studied by using an LKB-2277 BioActivity Monitor, ampoule method, at 37 degrees C. After isolation from the chicken liver tissue, mitochondria still have metabolic activity and can live for a long time by using the stored nutrients. From the thermogenic curves, we obtained the thermokinetic equations under different condition. The kinetic study shows that La3+ has changed the metabolism completely.

Animals↗
PubMed2001

T-cell adoptive therapy of tumors: mechanisms of improved therapeutic performance.

The T cells of many cancer patients are naturally sensitized to tumor-associated antigens (Ag), or they can readily be sensitized with vaccine maneuvers. In melanoma patients, the adoptive transfer of such T cells can often be causally linked to the objective regression of established tumors. So far, few patients have shown sustained clinical benefit from such therapy, but preclinical mouse studies have now clearly delineated the hurdles that must be overcome to render T-cell-based antitumor therapy effective. Contrary to earlier expectations, it is now established that remarkably potent CD4+ and CD8+ pre-effector T cells are naturally sensitized even in mice bearing progressive, weakly immunogenic tumors. However, such T cells often display signal transduction impairments as a consequence of the tumor environment, which limit their acquisition of optimal effector function. Extracorporealization and culture of these tumor-sensitized T cells with appropriate activation stimuli not only restores normal signal transduction, but also confers resolute effector activity that can often sustain tumor rejection upon reinfusion. In mouse studies, the L-selectin(low) fraction of T cells in tumor-draining lymph nodes (TDLN) constitutes the potent pre-effector population and comprises both CD4+ and helper-independent CD8+ T cells. Appropriate in vitro activation confers an apparently unrestricted trafficking capacity to this fraction, and even the ability to proliferate within the tumor bed, leading to unprecedented tumor rejection at anatomic sites (e.g., subcutaneous and intracranial) that were historically refractory to such treatment. Such results underscore the surprising capacity of appropriately activated effector T cells to withstand the immunosuppressive, tolerogenic, and apoptotic influences of the typical tumor environment. Given the increasingly appreciated and critical communications between T cells and host Ag-presenting cells (APC), which cross-present tumor Ag, it is likely that dendritic cell-based vaccine maneuvers that promote sensitization of T1-committed L-selectin(low) antitumor T cells will play an increasingly important role in adoptive therapy strategies.

Animals↗
PubMed2001

Nitric oxide in vPAG mediates the depressor response to acupuncture in stress-induced hypertensive rats.

The hypertensive rat model was made by chronic stress of electric foot-shocks and noises. On such hypertensive rats, when anesthetized with urethane and chloralose, the electroacupuncture (EA) to bilateral "Zusanli (st.36)" acupoints for 20 min, could result in a depressor (including both systolic and diastolic pressure) and bradycardiac response as well as an attenuation in the maximum of left ventricular pressure, end diastolic pressure and +/-dp/dt. In power spectrum analysis of heart rate variability aspect, EA could increase all total variance, very low frequency component, low frequency component and the ratio of low frequency component and high frequency component. When EA with microinjection of N(omega) - Nitro- L-Arginine , a blocker of the formation of nitric oxide, into the ventral periaqueductal gray matter (vPAG), the above effects of EA were abolished or reduced significantly. The results suggest that the depressor effect of EA on stress-induced hypertensive rats might be mediated by nitric oxide in the vPAG due to activation of sympathetic inhibitory system and by attenuated cardiac activities.

Acupuncture Points↗
PubMed2001

Anti-human platelet tetraspanin (CD9) monoclonal antibodies induce platelet integrin alpha IIb beta 3 activation in a Fc receptor-independent fashion.

OBJECTIVES: To characterize the activation of platelet integrin alpha IIb beta 3 induced by two anti-human platelet tetraspanin monoclonal antibodies (mAbs), HI117 and SJ9A4, and investigate their potential mechanism of action. METHODS: Using 125I-labeled human fibrinogen (Fg), specific Fg binding to human platelets induced by HI117 and SJ9A4 was measured. RESULTS: HI117 and SJ9A4 (10 micrograms/ml and 20 micrograms/ml) induced specific Fg binding to human platelets, suggesting that the two mAbs evoked activation of platelet integrin alpha IIb beta 3. Further study indicated that HI117 and SJ9A4 induced integrin alpha IIb beta 3 activation independent of platelet Fc-receptors, and that HI117 and SJ9A4-induced integrin alpha IIb beta 3 activation was inhibited by pretreatment of platelets with sphingosine, aspirin, apyrase, and/or PGI2. CONCLUSIONS: Anti-platelet tetraspanin (CD9) mAbs, HI117 and SJ9A4, can induce platelet integrin alpha IIb beta 3 activation independent of Fc-receptors. Three signaling pathways, namely thromboxane, secreted ADP, and cAMP pathways, may be involved in the process, with protein kinase C activation presumably being the common step of the three pathways.

Antibodies, Monoclonal↗
PubMed2001

[Docitaxol-induction apoptosis of osteosarcoma].

OBJECTIVE: To study the growth inhibition and apoptosis induction effect of docitaxol on osteosarcoma cells. METHODS: The effect of docitaxol on osteosarcomat cell line PL-1 was examined by cell count, morphologic observation, flow cytometry (FCM) and electronmicroscopy. RESULTS: Docitaxol inhibited the growth of PL-1 in a time and dose-dependent manner. The osteosarcoma cells were blocked at G1 phase of the cell cycle. The treated cells presented features typical of apoptosis. Cells recultured shortly after being treated with docitaxol were more apt to undergo apoptosis than cells treated with docitaxol continuously. CONCLUSION: The growth inhibiting effect of docitaxol is due to its ability to induce apoptosis. It shows great potential in the treatment of osteosarcoma.

Antineoplastic Agents, Phytogenic↗
PubMed2001

[Influence of specimen processing method on Mycobacterium tuberculosis detection by PCR-reversed dot hybridization].

OBJECTIVE: To evaluate specimen processing with sodium dodecyl (lauryl) sulfate (SDS) on the detection of Mycobacterium tuberculosis by PCR-reversed dot hybridization. METHODS: Totally 266 specimens were collected from sputum, pleural fluid, ascites, urine or blood of patients with active tuberculosis and were treated with SDS or routine method. All specimens handled were tested for detecting M. tuberculosis by PCR-reversed dot hybridization. RESULTS: The detection rate of M. tuberculosis from specimens prepared by SDS method was 65.0% (173/266) as compared with 51.5% (136/168) by routine method. Results from two methods were considered statistically significant (chi(2) = 35.03, P < 0.001). CONCLUSION: The SDS processing method may be used to detect M. tuberculosis from clinical specimens by PCR and enhances the detection rate of M. tuberculosis.

Detergents↗
PubMed2001

[Annexin V for flow cytometric detection of phosphatidylserine expression on lymphoma cells undergoing apoptosis].

OBJECTIVE: To quantitatively analyze apoptotic and secondary necrotic cells under apoptosis conditions. METHODS: The cells of Burkitt lymphoma cell line Raji were incubated with 1.0 mumol/L dexamethasone (DEX) for 2, 4 and 8 h, then stained with Annexin V-FITC (fluorescein isothiocyanate conjugated) which was used to detect the exposure of phosphatidylserine (PS) on the out membrane resulting from a loss of phospholipid asymmetry in the early stage of apoptosis, and also stained with propidium iodide (PI) which allows the analysis of secondary necrotic cells related with cell membrane and DNA damage, then apoptotic cells was quantified by flow cytometry (FMC). Furthermore, Annexin+/PI- and Annexin+/PI+ cells were sorted by fluoresence-activated cell sorter (FACS), and identified by electron microscopy (EM) and DNA gel electrophoresis. RESULTS: The results revealed that the percentage of apoptotic cells was increased and correlated well with incubation time (r = 0.97). The sensitivity of this method was shown by its detection limit 0.02%; the method was reproducible, and the coefficient variance (CV) was 4.2%. Meanwhile, the Annexin+/PI- and Annexin+/PI+ cells were identified as apoptotic and necrotic cells under EM, and the DNA extracted from the Annexin+/PI- cells was characterized by "ladder pattern". CONCLUSION: Annexin V assay for analyzing apoptotic cells is specific, sensitive, accurate, reproducible and quantitative for apoptosis investigation.

Annexin A5↗
PubMed2001

[Counting platelets by flow cytometry with platelet-specific antibody CD42a].

OBJECTIVE: To investigate a reference method for platelet (PLT) count. METHODS: 76 samples of daily whole blood of high, normal and low values in patients were collected and analyzed by flow cytometry (FCM) with CD42a monoclonal antibody that could combine specifically with the platelet membrane glycoprotein Ib-Ix (GPIb-Ix). PLT counts were analyzed by multiplying PLT/RBC ratio from FCM with the RBC that was counted by a calibrated blood analyzer. Meanwhile, the results of PLT from FCM were compared with that from blood analyzers SE-9500, NE-1500, CD-1600 or manual count. RESULTS: The within-replicate coefficient of variance(CV) of FCM was less than 4% for a high count(501 x 10(9)/L) and middle count(184 x 10(9)/L), the CV of low count(23 x 10(9)/L) was 11.432%, the between-replicate CV was 10.792%, and the overall reproducibility was less than 5%. Linearity was demonstrated well(r = 0.9975 P < 0.001) when the PLT counts were 20 x 10(9)/L-700 x 10(9)/L. PLT count was stable at room temperature within 6 hr. The carry-over was 0.87%. The results between FCM and SE-9500, NE-1500, CD-1600 or manual count was comparable (r > 0.975, P < 0.001). CONCLUSION: These findings confirm that FCM for PLT count is specific, accurate and precise and could be considered as a candidate of reference method for PLT count.

Antibodies, Monoclonal↗
PubMed2001

[Application of posterior canal wall reconstruction and mastoid obliteration].

OBJECTIVE: To explore the obliteration of the old mastoid cavity and reconstruction of the posterior canal wall after radical mastoidectomy. METHOD: Posterior canal wall reconstruction and mastoid obliteration of 11 ears of 10 patients with old mastoid cavity for 1 to 6 years after radical mastoidectomy were done using the pedicle postauricular composite skin flap (PPCSF), and their tympanoplasty were performed at the same time. Follow-up was performed at 3 to 30 months. RESULT: All PPCSFs survived. The old mastoid cavity of 11 ears vanished and reconstructed posterior canal wall remained in normal position without retraction. The drying ear time took 2 to 3 weeks postoperatively, and the symptoms of the radical cavity disease after radical mastoidectomy were cleared up nearly, and the average hearing threshold decreased 13.6 dB HL. The otorrhea and perforation of tympanic membrane resulted from infection happened to 1 of 11 ears three month after the operation. CONCLUSION: The PPCSF is an effective method in the obliteration of old mastoid cavity and reconstruction of the posterior canal wall. It can reduce drying ear time postoperatively, treat the radical cavity disease after radical mastoidectomy and is beneficial to the tympanoplasty at the posterior external at the same time.

Adolescent↗
PubMed2001

[Investigation of the effects of various factors affecting apoptosis of chronic lymphocytic leukemic cells mediated by P2Z receptors].

OBJECTIVE: To explore the effects of various factors affecting apoptosis of chronic lymphocytic leukemia (CLL) cells mediated by P2Z purinoceptor. METHODS: In vitro exposure of CLL cells with P2Z receptors to 1 mmol/L ATP or 0.1 mmol/L benzoylbenzoic ATP (BzATP) for 8 h in the presence of 1.0 mmol/L Mg2+ or other bivalent cations, 150 mmol/L choline in media, 1, 2, 4 mmol/L EDTA or EGTA, or under different temperature. ATP-induced apoptosis was detected by agarose gel electrophoresis, TdT assay and flow cytometric analysis (FCA). RESULTS: The results showed that 1. Extracellular Mg2+ or Ca2+ stimulated ATP-induced DNA fragmentation in a dose-dependent manner, and the compatible evidence was provided by the inhibition of ATP-induced DNA fragmentation in the presence of EGTA or EDTA; 2. ATP-induced DNA fragmentation was completely inhibited by 1.0 mmol/L Zn2+; 3. ATP-induced DNA breaks were not affected by Ba2+, Sr2+, Co2+ when they were substituted for extracellular Mg2+ or Ca2+; 4. Choline, an inhibitor of phospholipase D (PLD) stimulated by ATP through P2Z receptor in human lymphocytes, was also a partial inhibitor of ATP-induced DNA fragmentation, and the results were confirmed by flow cytometric analysis (FCA); 5. ATP-induced DNA fragmentation was completely obliterated when the temperature was lower than 10 degrees C. CONCLUSION: These results suggest that the endonuclease and PLD may be involved in ATP-induced apoptosis in human lymphocytes via P2Z receptor.

Adenosine Triphosphate↗
PubMed2000

T cell-mediated tumor rejection displays diverse dependence upon perforin and IFN-gamma mechanisms that cannot be predicted from in vitro T cell characteristics.

Experimental pulmonary metastases have been successfully treated by adoptive transfer of tumor-sensitized T cells from perforin knockout (KO) or Fas/APO-1 ligand(KO) mice, suggesting a prominent role for secretion of cytokines such as IFN-gamma. In the present study we confirmed that rejection of established methylcholanthrene-205 (MCA-205) pulmonary metastases displayed a requirement for T cell IFN-gamma expression. However, this requirement could be obviated by transferring larger numbers of tumor-sensitized IFN-gamma (KO) T cells or by immunosensitizing sublethal irradiation (500 rad) of the host before adoptive therapy. Extrapulmonary tumors (MCA-205 s.c. and intracranial) that required adjunct sublethal irradiation for treatment efficacy also displayed no requirement for host or T cell expression of IFN-gamma. Nonetheless, rejection of MCA-205 s.c. tumors and i.p. EL-4 tumors, but not MCA-205 pulmonary or intracranial tumors, displayed a significant requirement for T cell perforin expression (i.e., CTL participation). The capacity of T cells to lyse tumor targets and secrete IFN-gamma in vitro before adoptive transfer was nonpredictive of the roles of these activities in subsequent tumor rejection. Adoptive therapy studies employing KO mice are therefore indispensable for revealing a diversity of tumor rejection mechanisms that may lack in vitro correlation due to delays in their induction. Seemingly contradictory KO data from different studies are reconciled by the capacity of anti-tumor T cells to rely on alternative mechanisms when treated in larger numbers, the variable participation of CTL at different anatomic locations of tumor, and the apparent capacity of sublethal irradiation to provide a therapeutic alternative to host or T cell IFN-gamma production.

Animals↗
PubMed2000

Helper-independent, L-selectinlow CD8+ T cells with broad anti-tumor efficacy are naturally sensitized during tumor progression.

We recently reported that the CD4(+) T cell subset with low L-selectin expression (CD62L(low)) in tumor-draining lymph nodes (TDLN) can be culture activated and adoptively transferred to eradicate established pulmonary and intracranial tumors in syngeneic mice, even without coadministration of IL-2. We have extended these studies to characterize the small subset of L-selectin(low) CD8(+) T cells naturally present in TDLN of mice bearing weakly immunogenic tumors. Isolated L-selectin(low) CD8(+) T cells displayed the functional phenotype of helper-independent T cells, and when adoptively transferred could consistently eradicate, like L-selectin(low) CD4(+) T cells, both established pulmonary and intracranial tumors without coadministration of exogenous IL-2. Whereas adoptively transferred L-selectin(low) CD4(+) T cells were more potent on a cell number basis for eradicating 3-day intracranial and s.c. tumors, L-selectin(low) CD8(+) T cells were more potent against advanced (10-day) pulmonary metastases. Although the presence of CD4(+) T cells enhanced generation of L-selectin(low) CD8(+) effector T cells, the latter could also be obtained from CD4 knockout mice or normal mice in vivo depleted of CD4(+) T cells before tumor sensitization. Culture-activated L-selectin(low) CD8(+) T cells did not lyse relevant tumor targets in vitro, but secreted IFN-gamma and GM-CSF when specifically stimulated with relevant tumor preparations. These data indicate that even without specific vaccine maneuvers, progressive tumor growth leads to independent sensitization of both CD4(+) and CD8(+) anti-tumor T cells in TDLN, phenotypically L-selectin(low) at the time of harvest, each of which requires only culture activation to unmask highly potent stand-alone effector function.

Adenocarcinoma↗