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Biomedical subjects

Q Chen

Publications and source records attributed to Q Chen.

At least 253 records · Page 14Linked to original sources
PubMed2000

A direct comparison of cytolytic T-lymphocyte responses to Melan-A peptides in vitro: differential immunogenicity of Melan-A27-35 and Melan-A26-35.

In this study we directly compared the in vitro responses of T-cells from normal donors and melanoma patients to Melan-A27-35 and Melan-A26-35. These peptides have been previously used in peptide-based vaccination studies. Following three stimulations with peptide-pulsed antigen-presenting cells in vitro, Melan-A-specific cytolytic T-lymphocytes (CTLs) were generated from seven of 20 subjects; two of the seven subjects responded reproducibly to both Melan-A27-35 and Melan-A26-35, three to only Melan-A27-35 and two to only Melan-A26-35. However, CTLs generated with either Melan-A27-35 or Melan-A26-35 showed cross recognition, and both types of CTL could recognize naturally processed antigen displayed on HLA-A2+ tumour cells. Furthermore, Melan-A-specific CTLs could also be generated by stimulating peripheral blood mononuclear cells with autologous melanoma cells. Our results suggest that some subjects may have a bias in their CTL repertoire which favours the generation of Melan-A27-35 specific CTLs, while others may favour Melan-A26-35 specific CTLs. It is also likely that CTL precursors capable of detecting both peptides may have different affinities to the two Melan-A peptides. Since it is difficult to predict the CTL responses to Melan-A peptide in a given individual, we suggest vaccinating with both Melan-A27-35 and Melan-A26-35 peptides in clinical trials.

Cancer Vaccines↗
PubMed2000

Novel techniques for MR imaging of pulmonary airspaces.

Hyperpolarized gas- and molecular oxygen-enhanced MR imaging are two new techniques for high-resolution MR imaging of pulmonary airspaces. Both techniques produce excellent images in a safe, reproducible, and technically feasible manner. Because morphologic and functional information is obtained, and radiation is not used, these techniques may prove ideal for serially evaluating patients with a variety of lung diseases that affect pulmonary ventilation, such as cystic fibrosis, emphysema, asthma, or bronchiolitis obliterans syndrome in lung transplant recipients. At present, the greatest clinical experience is with hyperpolarized He-3-enhanced MR imaging. This technique is limited, however, by the limited availability of He-3, by its polarization requirements, and by the need to tune the MR system to the resonant frequency of the gas. There is less clinical experience with oxygen-enhanced MR imaging. Although this technique produces images with more inherent noise than hyperpolarized He-3 imaging, this problem can be overcome by signal averaging. Oxygen-enhanced imaging has the major advantages of lower cost and ready availability. For oxygen-enhanced imaging, the MR imaging system does not need to be readjusted; imaging is performed at the conventional hydrogen proton frequency.

Animals↗
PubMed2000

Growth of the fungal pathogen Candida in parotid saliva of patients with burning mouth syndrome.

Subclinical Candida infection has been suggested as one of the aetiological factors in patients with burning mouth syndrome (BMS). In order to investigate the possible factors which contribute to the relatively high isolation rate of Candida in BMS, parotid saliva samples (20 in toto) from patients with this condition were collected and the growth of Candida in each sample dynamically observed using a computerized turbidometric assay system. A total of thirteen parotid saliva samples obtained from healthy individuals served as normal controls. The results showed no significant growth differential within the test and control saliva samples, when a single isolate each of Candida albicans and Candida tropicalis were cultured for 24 h, at 37 degrees C. A single isolate of Candida glabrata tended to grow better in the saliva from BMS patients than the controls. These results indicate that the composition of saliva may be a contributory factor for the high isolation rate of Candida in saliva of BMS patients.

Adult↗
PubMed2000

[Evaluation for biocompatibility of poly-(3-hydroxypropyl)-DL-aspartamide].

To evaluate the biocompatibility of poly-(3-hydroxypropyl)-DL-aspartamide(PHPA), we utilized the laboratory methods, including subcutaneous implantation, histological examination, blood biochemical and micronucleus test. Histological examination revealed a nonspecific foreign body reaction around the PHPA and a slight inflammation around the small blood vessels of the liver on the 13th day, but all these reactions diminished or disappeared gradually after 34 days of implantation. The structures and functions of liver and kidney were normal. The results indicate that PHPA possesses a good nature in biocompatibility.

Alanine Transaminase↗
PubMed2000

Human neutrophil defensins selectively chemoattract naive T and immature dendritic cells.

Defensins, a family of cationic, structurally related, antimicrobial peptides, contribute to host defense by disrupting the cytoplasmic membrane of microbes. Here we show that human neutrophil defensins selectively induce the migration of human CD4+/CD45RA+ naive and CD8+, but not CD4+/CD45RO+ memory, T cells. Moreover, human neutrophil defensins are chemotactic for immature human dendritic cells derived from either CD34+ progenitors or peripheral blood monocytes. Upon maturation induced by treatment with tumor necrosis factor alpha (TNF-alpha), dendritic cells lose their responsiveness to human neutrophil defensins. The chemotactic effect of human neutrophil defensins on both T and dendritic cells is pertussis toxin-sensitive, suggesting that a G(ialpha) protein-coupled receptor is responsible. Human neutrophil defensins are also chemotactic for immature murine dendritic cells. These data suggest that, in addition to their antimicrobial role, human neutrophil defensins also contribute to adaptive immunity by mobilizing T cells and dendritic cells.

Adult↗
PubMed2000

The optimal outcomes of post-hospital care under medicare.

OBJECTIVE: To estimate the differences in functional outcomes attributable to discharge to one of four different venues for post-hospital care for each of five different types of illness associated with post-hospital care: stroke, chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), hip procedures, and hip fracture, and to estimate the costs and benefits associated with discharge to the type of care that was estimated to produce the greatest improvement. STUDY SETTING/DATA SOURCES: Consecutive patients with any of the target diagnoses were enrolled from 52 hospitals in three cities. Data sources included interviews with patients or their proxies, medical record reviews, and the Medicare Automated Data Retrieval System. ANALYSIS: A two-stage regression model looked first at the factors associated with discharge to each type of post-hospital care and then at the outcomes associated with each location. An instrumental variables technique was used to adjust for selection bias. A predictive model was created for each patient to estimate how that person would have fared had she or he been discharged to each type of care. The optimal discharge location was determined as that which produced the greatest improvement in function after adjusting for patients' baseline characteristics. The costs of discharge to the optimal type of care was based on the differences in mean costs for each location. DATA COLLECTION/EXTRACTION METHODS: Data were collected from patients or their proxies at discharge from hospital and at three post-discharge follow-up times: six weeks, six months, and one year. In addition, the medical records for each participant were abstracted by trained abstractors, using a modification of the Medisgroups method, and Medicare data were summarized for the years before and after the hospitalization. PRINCIPAL FINDINGS: In general, patients discharged to nursing homes fared worst and those sent home with home health care or to rehabilitation did best. Because the cost of rehabilitation is high, greater use of home care could result in improved outcomes at modest or no additional cost. CONCLUSIONS: Better decisions about where to discharge patients could improve the course of many patients. It is possible to save money by making wiser discharge planning decisions. Nursing homes are generally associated with poorer outcomes and higher costs than the other post-hospital care modalities.

Activities of Daily Living↗
PubMed2000

Characterization of wheat-Thinopyrum partial amphiploids by meiotic analysis and genomic in situ hybridization.

A combination of genomic in situ hybridization (GISH) and meiotic pairing analysis of wheat-Thinopyrum partial amphiploids was employed to identify the genomic constitution and relationships between partial amphiploids derived from wheat and wheatgrass crosses. On the basis of similarities in the meiotic behavior and GISH patterns, the alien chromosomes of two of eight partial amphiploids, TAF46 and 'Otrastayuskaya 38', were judged to originate from Th. intermedium, whereas Th. ponticum was one of the parents of the other six partial amphiploids; PWM706, PWM206, PWM209, PWMIII, OK7211542, and Ag-wheat hybrid. Each of these partial amphiploids was found to contain a synthetic alien genome composed of different combinations of St-, J-, or Js-genome chromosomes. For relatedness of partial amphiploid lines, meiotic analysis of F1 hybrids and GISH results were generally complementary, but the latter offered greater precision in identifying constituent genomes.

Blotting, Southern↗
PubMed2000

Induction of cell cycle entry and cell death in postmitotic lens fiber cells by overexpression of E2F1 or E2F2.

PURPOSE: Previous studies have shown that inactivation of the retinoblastoma tumor suppressor protein (pRb) can cause lens fiber cell proliferation and apoptosis. Because pRb is thought to block cell cycle progression by inhibition of E2F transcription factors, experiments were conducted to test whether overexpression of different E2F family members would be sufficient to induce fiber cell proliferation and subsequent apoptosis. The in vivo functions of the transcription factor E2F2 have not previously been analyzed or described in transgenic mice. METHODS: Human E2F1 and E2F2 cDNAs were linked to the alphaA-crystallin promoter. Transgenic mice were generated by microinjection. Changes in cell cycle regulation were assayed by immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU) incorporation and by in situ hybridization. Cell death was assayed using the TdT-dUTP terminal nick-end labeling (TUNEL) assay. RESULTS: At embryonic day (E)15.5, strong expression of the E2F1 and E2F2 transgenes was detected in lens fiber cells with little or no expression in epithelial cells. BrdU incorporation and TUNEL assays showed that overexpression of either E2F1 or E2F2 in lens fiber cells was sufficient to cause cell cycle entry and subsequent apoptosis. Expression of either E2F1 or E2F2 was sufficient to induce the transcription of cyclins (A2, B1, and E), as well as p53 and Bax in the lens fibercells. CONCLUSIONS: Expression of either E2F1 or E2F2 can induce postmitotic lens fiber cells to re-enter the cell cycle. Inappropriate cell cycle entry is recognized by p53 in each case, and programmed cell death ensues.

Animals↗
PubMed2000

Expression of renin-angiotensin system and extracellular matrix genes in cardiovascular cells and its regulation through AT1 receptor.

Angiotensinogen (AGT) is a unique substrate of the renin-angiotensin system and fibronectin (FN) is an important component of the extracellular matrix. These play critical roles in the pathophysiological changes including cardiovascular remodeling and hypertrophy in response to hypertension. This study was performed to examine the regulation of AGT and FN gene in cardiac myocytes (CMs) and vascular smooth muscle cells (VSMCs) in response to mechanical stretch. Mechanical stretch significantly increased the AGT mRNA expression in CMs, while these stimuli did not affect FN mRNA levels. On the other hand, mechanical stretch upregulated FN mRNA levels in VSMCs, whereas no increase in AGT mRNA levels was observed in response to stretch stimuli. An angiotensin II type 1 (AT1) receptor antagonist (CV11974) significantly decreased these stretch-mediated increases in mRNA level and promoter activity of the AGT and FN gene, whereas angiotensin II type 2 (AT2) receptor antagonist (PD 123319) did not affect the induction. These results indicate that mechanical stretch activates transcription of the AGT and FN gene mainly via AT1 receptor-pathway in CMs and VSMCs. Furthermore, mechanisms regulating AGT and FN gene seem to be different between CMs and VSMCs.

Angiotensin Receptor Antagonists↗
PubMed2000

[Detection of differentially expressed genes in hepatocellular carcinoma using DNA microarray].

Large scale gene expression profiles between normal hepatocytes and hepatocellular carcinomas are detected with high throughput microarray. DNA microarrays were made by spotting PCR products of 4,096 human cDNAs onto a specially treated glass slides. The probes were prepared by labelling normal tissue mRNA and cancer tissue mRNA with Cy3-dUTP and Cy5-dUTP separately through reverse transcription. The arrays were then hybridized against the cDNA probe mixture and the fluorescent signals were scanned. The obtained data were analyzed from 4 repeated experiments. There are 903 genes of which the average ratios between Cy3 signal and Cy5 signal are greater than 3.0. These genes identified through this approach are potential candidates for hepatocellular carcinoma diagnosis and therapy.

Carcinoma, Hepatocellular↗
PubMed2000

[The effect of adding cefobid upon the physiochemical properties of calcium phosphate cement].

This study was conducted to analyze the physiochemical properties of different mass ratio compounds of cefobid-load calcium phosphate cement(CPC). The compounds of 0%, 2.9%, 4.8% and 7.4% mass ratio cefobid-load CPC were made respectively. The setting time was observed; the compressive strength of compounds was measured by a material testing machine; the construction of compounds was observed by scanning electron microscopy(SEM) and analyzed by EIG. The results showed that both the setting time and the ratio of hole did not change obviously after the addition of cefobid, but the ultimate compressive strength decreased slowly and the results of the four groups were (21.98 +/- 1.06)MPa, (21.38 +/- 0.95)MPa, (19.22 +/- 1.11)MPa and (13.5 +/- 1.65)MPa respectively. These data indicate there is no obvious effect on the physicochemical properties of calcium phosphate cement after the addition of cefobid between 0% and 4.8%. The compounds have irregular holes and hence a good ability of compressive strength. It might be a new bone grafting material for the reparation of infection-related bone defects.

Biomechanical Phenomena↗
PubMed2000

[Analysis of ultrasonic backscattering microstructure feature of human spleen based on "WD cepstrum"].

A new method "WD cepstrum" for analysing ultrasonic scattered signals based on wavelets decomposition before cepstrum has been developed and then applied to process the backscattered signals of normal and pathological human spleen in vitro. The mean scatterer spacing(MSS) has been estimated. The results show that the MSS data of the two tissues are quite different and "WD cepstrum" is more effective for reflecting the microstructure feature of tissue. The results also illustrate that "WD cepstrum" is an effective method for signal analysis of ultrasonic scattering and characterization of tissue scatterers.

Humans↗
PubMed2000

[Analysis on genetic polymorphism of mtDNA in endurance athletes and sedentary subjects].

AIM: To analysis the sequence variation of the origin region (D-loop) of mitochondrial DNA (mtDNA) in elite endurance athletes and sedentary subjects in order to find the genetic markers related with performance. METHODS: Using a new established PCR method by virtue of tracing sample analysis, the restricted fragment length polymorphism (RFLP) of D-loop in mtDNA was assessed in 76 elite Chinese endurance athletes (EEA), 33 endurance athletes with average-level(GEA) and 20 sedentary control(sc). RESULTS: There is a significant difference in distribution of the polymorphism in mtDNA D-loop between the EEA and SC(chi 2 = 33.3, P < 0.01). CONCLUSION: The sequence variation of D-loop region of mtDNA in the elite endurance athletes may contribute to the individual difference in aerobic performance and trainability.

Adult↗
PubMed2000

[The study of mechanism by which mild hypothermia reduced delayed neuronal death after cerebral ischemia in gerbils].

AIM: To study the effect of mild hypothermia on delayed neuronal death as well as the relationship between hydroxyl radicals generation in hippocampus and the change of dopamine and ATP content in striatum following ischemia/reperfusion in gerbils. METHODS: The ischemia was induced by occlusion the both carotid common arteries for 10 minutes in gerbils. Animals were divided into four groups: sham-operated group, ischemic group, ischemia/reperfusion group and mild hypothermic ischemia/reperfusin group. The numbers of delayed neuronal death were assessed by histological examination. OH. outputs in hippocampus and dopamine content in striatum were specifically identified and quantitated by high performance liquid chromatography (HPLC) coupled with electrochemical detection (ECD). ATP content in striatum was also determined by HPLC. RESULTS: Mild hypothermia significantly reduced the numbers of damaged neurons in hippocampus CA1 subfield after ischemia in gerbils. In MH group, 2,3-DHBA outputs were much less than that in IR group (P < 0.01). Dopamine and ATP content in striatum were higher than those in IR group (P < 0.01). CONCLUSION: Mild hypothermia could decrease the delayed neuronal death in gerbils by reducing hydroxyl radicals production in hippocampus and inhibiting dopamine release as well as prompting the recovery of ATP content in striatum following ischemia/reperfusion in gerbils.

Animals↗
PubMed2000

Influence of batroxobin on cerebral ischemia-reperfusion injury in gerbils.

AIM: To study the effects of batroxobin (Bat) on neurons survival, neurobehavioral test, ATP levels and hydroxyl radical outputs in hippocampus during forebrain ischemia-reperfusion in gerbils. METHODS: The forebrain ischemia was induced by occluding the bilateral common carotid arteries for 10 min in gerbils, and ATP levels and 2, 3-dihydroxybenzoic acid (DHBA) outputs were assayed by HPLC. The neurons survival were assessed by histology, and behavioral tests of gerbils were assessed by open field test. RESULTS: The number of neurons survival in Ir at d 7 postischemic insult were (7 +/- 4)% of sham-operated gerbils, much less than that in Bat (45 +/- 16)%. The levels of explore activities of ischemic gerbils was 175% and 159% of sham-operated gerbils at d 3 and d 6 postischemic insult, much more than that in Bat (120% d 3 and 140% d 6). Hippocampal ATP levels in Ir were 64% of sham-operated gerbils at reperfusion 60 min, much less than that in Bat I and II (82% and 89% respectively). The hippocampal 2,3-DHBA outputs in Ir increased by 4.5 folds of sham-operated gerbils at reperfusion 60 min, but the 2,3-DHBA outputs in Bat I and Bat II were only 2.6 and 2.4 folds respectively. CONCLUSION: Bat possesses the inhibitory effects on DND and OH. production following cerebral ischemia-reperfusion in gerbils.

Adenosine Triphosphate↗
PubMed2000

[Human umbilical cord used for wrapping hydroxyapatite orbital implant--animal experiment and clinical observation].

OBJECTIVE: Hydroxyapatite (HA) sphere is admitted to be the best orbital implant today, but it can cause some complications, such as conjunctival erosion and implant exposure. The causes of these complications include HA's mechanical and chemical stimulation to the conjunctiva. In order to protect conjunctiva against HA's invasion, most authors suggest wrapping the HA sphere with some material. The wrapping materials usually are autogenous or heterogeneous sclera or fascia. These materials are either unavailable or unaccepted by patients. This study was made on human umbilical cord tissue as the wrapping material of HA sphere. METHOD: Hydroxyapatite spheres enveloped in human umbilical cord tissue were inserted in ten rabbits' orbits. At 1, 2 weeks and 1, 2, 3, 6, 8, 10, 12 and 14 months after implantation, the conjunctival sac was examined. Then the HA sphere was removed and examined with a scanning electron microscope. Fifteen patients received HA orbital implants enveloped in human umbilical cord from September 1996 To December 1997. The pre- and post-operative photographs of the sockets, the implant motility were analysed. RESULTS: The animal experiment showed that the umbilical cord was tightly adherent to the HA sphere and orbital tissue. The fibro-vascular tissue gradually invaded the interconnecting pores of the sphere after implantation. None of the 15 patients had orbital infection or implant extrusion during an average follow-up of 10 months (range of 8-12 months). Three patients had conjunctival erosion, which was well treated. All patients have cosmetically satisfactory motility of the prosthesis. CONCLUSION: Human umbilical cord tissue can be used as wrapping material of hydroxyapatite orbital implant.

Adolescent↗
PubMed2000

[Effect of Nerium indicum on killing Oncomelania hupensis].

A laboratory experiment at 20 +/- 5 degrees C shows that the water extract of fresh Nerium indicum had an obvious effect on killing Oncomelania hupensis. Treated with 0.1% water extract for four days, the mortality of O. hupensis was up to 100%. The effect of different tissues of N. indicum on O. hupensis was in order of stem phloem > leaf > root phloem > flower. The effect of N. indicum on O. hupensis was about ten times higher than that of Pterocarya stenoptera and Rumex japonicus, and was equal to that of 1 x 10(-3) mg.L-1 niclosamidum.

Animals↗