Biomedical subjects

Dan Xu

Publications and source records attributed to Dan Xu.

49 records · Page 3Linked to original sources

PubMed2003

Monochromatic wavefront aberrations in the human eye with contact lenses.

PURPOSE: The aim of this study was to investigate the effect of contact lenses on the optical performance of the eye by measuring wavefront aberrations for the eyes with or without contact lenses. METHOD: A sensitive aberrometer was used to measure wavefront aberrations for 54 eyes in 27 subjects for three conditions: with no contact lens (non-CL), with soft-contact lenses (soft-CL) and with rigid gas permeable contact lenses (RGP-CL). The root mean square (RMS) value of the wavefront aberrations and Zernike aberrations were calculated. RESULTS: A change in the RMS values of wavefront aberrations with CL wear was observed for every eye. The change in wavefront aberrations with CL wearing was found to vary substantially from individual to individual. Relative to the mean RMS value of the group for the non-CL condition, the mean RMS value was increased for the soft-CL condition and was significantly reduced for the RGP-CL condition. A significant increase in mean RMS for the soft-CL condition was found when astigmatisms were removed. Although soft-CL wearing resulted in significant increases in higher orders of Zernike aberrations (fourth, fifth, and higher), the RGP-CL condition led to a significant decrease in second-order Zernike aberrations. For the eyes with low wavefront aberrations in the non-CL condition, either soft-CL wearing or RGP-CL wearing results in increases in the RMS values. CONCLUSION: Contact lens wearing, either with soft lenses or the RGP lenses, causes changes in the wavefront aberrations of the eye. The changes in wavefront aberrations vary substantially from eye to eye. Although soft-CL wearing tends to induce more higher-order aberrations, RGP-CL effectively reduces the astigmatisms. Both soft-CL and RGP-CL induce more aberrations for the eyes that have low wavefront aberrations. The change in wavefront aberrations due to contact lens wearing may explain the changes in visual performance for contact lens wearers reported previously.

Adolescent↗

PubMed2003

[Study of murine hematopoietic stem/progenitor cell mobilized by recombinant human interleukin 11 combination with granulocyte-colony stimulating factor].

OBJECTIVE: To study the recombinant human interleukin 11 (rhIL-11) in combination with granulocyte-colony stimulating factor (rhG-CSF) for mobilizing peripheral blood stem/progenitor cells in C57BL/6 mice. METHODS: rhIL-11,250 micro g x kg(-1) x d(-1) per mouse alone or in combination with rhG-CSF 250 micro g x kg(-1) x d(-1) per mouse was administered to C57BL/6 mice from day 1 to 7. The changes of peripheral white blood cell count (WBC), platelet counts (BPC) and hematopoietic stem/progenitor cells yields were observed. RESULTS: The results showed that rhIL-11 alone or in combination with rhG-CSF resulted in increase in absolute numbers of WBC, BPC, CD(34)(+) cells, and CFU-GM, CFU-E, CFU-MK yields in peripheral blood more than those of control (P < 0.001). The yields of CFU-MK was significantly more than that of rhG-CSF group (P < 0.001). CONCLUSION: rhIL-11 alone or in combination with G-CSF could significantly mobilize hematopoietic stem/progenitor cells from bone marrow into peripheral blood.

Animals↗

PubMed2003

[Experimental study of optimized H-2 haploidentical hematopoietic engraftment for the treatment of murine acute leukemia model].

OBJECTIVE: To explore the critical dose of T lymphocyte for preserving graft versus leukemia (GVL) while preventing GVHD in murine acute leukemia model treated with H-2 haploidentical hematopoietic stem cell transplantation (HSCT). METHODS: (C57BL/6 x 615) F1 (H-2bk) mice which was inoculated with L615 cells to develop leukemic murine model was the recipient. The healthy C57BL/6 (H-2b) mice was the donor. CD(34)(+) cells from bone marrow and CD(3)(+)cells from spleen of the donor were purified by miniMACS. The purity of CD(34)(+) cells and CD(3)(+) cells were (81.5 +/- 2.4)% and (95.4 +/- 2.9)% respectively. Sixty-nine recipient mice were divided into seven groups. Group A received no treatment, group B received TBI only, the rest groups were irradiated 9 Gy by (60)Co and transfused 10(5) CD(34)(+) cells or mixed with 10(7) (E), 10(8) (F), 1.5 x 10(8) (G) of CD(3)(+) cells respectively. The mice were raised for 60 days, The cause of death was identified by pathology. RESULTS: All mice in group E survived more than 60 days being significantly longer than that in the rest groups (p < 0.0001). The chimerisms from donor were 100% in the mice survived > 60 days. Mice died of leukemia relapse in group D and group E were significantly less than those in group C (p < 0.001). Mice died from GVHD in group G were significantly more than those in group E and group F (p < 0.001). CONCLUSIONS: The leukemia relapse rate was highest in mice that were transplanted with CD(34)(+) cells alone. Those mice transfused with CD(3)(+) T lymphocyte in the graft higher than 10(8) cells died from the GVHD was significantly higher. The inclusive dosage of 5 x 10(7) CD(3)(+) T lymphocyte was enough to separate the GVHD from GVL.

Animals↗

PubMed2003

[Role of vascular endothelial growth factor (VEGF) in development and progress of refractory acute myeloid leukemia].

BACKGROUND & OBJECTIVE: The mechanism of refractory leukemia is very complex. Recent studies have shown that overexpression of vascular endothelial growth factor (VEGF) was detected in bone marrow from acute myeloid leukemia (AML) patients, suggesting it may play an important role in AML. However,the effect of VEGF in the development of refractory leukemia is not clear. The current study was designed to explore the effect of overexpression of VEGF on the abnormal proliferation and harringtonine-induced apoptosis of HL-60 cells and to observe VEGF expression in the progression of refractory AML. METHODS: HL-60 cells were transfected with the VEGF(165)cDNA sense vector (HL-60/VEGF(165)) and with the pcDNA3.1-vector (HL-60/neo) as the control using lipofectamine. Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine VEGF mRNA. VEGF concentrations in the cell cultural supernatant were determined by enzyme linked immunosorbent assay (ELISA). Cell proliferation was determined by MTT and colony forming assay in vitro.Flow cytometric Annexin-V-FITC/PI dual labeling technique was performed to observe the effect of VEGF(165) cDNA transfection on harringtonine-induced apoptosis of HL-60 cells. ELISA was used to detect VEGF concentrations in the plasma from refractory and non-refractory AML patient. RESULTS: The mean VEGF concentration in the cell cultural supernatant of HL-60/VEGF(165) cells (399.07+/-12.45 ng/L) was 2-folds higher than that in HL-60/neo cells (184.45+/-10.53 ng/L)(P< 0.01). The VEGF(165)cDNA sense vector transfected HL-60 exhibited a 2-fold increase in VEGF secretion. The growth rate of HL-60/VEGF(165) cells was significantly higher than those of the controls, and colony formation capacity of HL-60/VEGF(165) increased significantly(P< 0.05);the colony numbers were (157.00+/-17.00)/500 cells and (110+/-12.90)/500 cells for HL-60/VEGF(165) and HL-60/neo, respectively. HL-60/VEGF(165) had less apoptotic cells than HL-60/neo in the same culture condition. High expression of VEGF could reduce the harringtonine-induced apoptosis of HL-60 cells. Refractory AML patients had higher mean plasma VEGF levels (558.90+/-271.25 ng/L) than non-refractory patients(392.54+/-217.82 ng/L), and significant difference was observed between them (P< 0.05). CONCLUSION: VEGF expression in refractory AML patients is higher than that in non-refractory AML patients. VEGF plays an important role in the abnormal proliferation and apoptosis of AML cells. High expression of VEGF could reduce the harringtonine- induced apoptosis of HL-60 cells.

Adult↗

PubMed2003

[Prevalence and characteristics of cerebral amyloid angiopathy in the elderly].

OBJECTIVE: To study the prevalence and clinico-neuropathological characteristics of Cerebral amyloid angiopathy (CAA) in Chinese elderly. METHODS: We examined 362 archived brains of aged Chinese from 60 to 95 years of age using an antibody against beta-amyloid peptide and with Gongo red, Bodian and Luxol fast blue stains. RESULTS: CAA appeared in 114 examined brains and the incidence rate in age groups of 60 - 69, 70 - 79, 80 - 89 and beyond 90 years was 22.1%, 26.7%, 46.5% and 66.7% separately; frontal lobe was the most frequently CAA involved part of brain; CAA may also distribute in subcortical white matter and cerebellum dentatus nucleus; close relationships were found between CAA and multiple cerebrovascular lesions, consequent dementia and Alzheimer disease; without other neuropathological changes, CAA alone may result in dementia. CONCLUSIONS: CAA is a common neuropathological finding in brains of Chinese elderly, with an increased prevalence with age. CAA may distribute in subcortical white matter and cerebellum dentatus nucleus, which have been seldom reported before and may contribute to vascular lesions in these areas. CAA may not only participate in the pathogenesis mechanisms of Alzheimer's disease and vascular dementia, but also result in dementia directly through cerebral hypoperfusion and chronic neuronal ischemia.

Age Factors↗

PubMed2003

[Effect of autocrine vascular endothelial growth factor on the biological activity of acute myeloid leukemia cell line HL-60].

OBJECTIVE: To explore the effect of autocrine vascular endothelial growth factor (VEGF) on the abnormal proliferation of HL-60 cells. METHODS: HL-60 cells were transfected via lipofictamine with the VEGF(165) cDNA sense vector (HL-60/ VEGF(165)) and with the PcDNA3.1(-)-vector (HL-60/neo) as the control. Reverse transcription-polymerase chain reaction (RT-PCR) was used for detecting VEGF mRNA in the transfected cells. VEGF concentrations in the cell culture supernatant were determined by enzyme-linked immunosorbent assay (ELISA), and cell proliferation was determined by MTT assay and colony-forming assay in vitro. Flow cytometric Annexin-V-FITC/ PI dual-labeling technique was employed to observe the effect of VEGF(165) cDNA transfection on the apoptosis of HL-60 cells. RESULTS: The levels of VEGF mRNA expression by HL-60/VEGF(165) cells were higher than HL-60/neo, with the mean VEGF quantity in the supernatant of HL-60/VEGF(165) cell culture being 399.07+/-12.45 ng/L, which was 2-fold higher than that in the supernatant of HL-60/neo cells (184.45+/-10.53 ng/L) (P<0.01). The growth rate of HL-60/VEGF(165) cells was significantly accelerated as compared with that of the control cells, and the colony formation capacity of the former cells also increased significantly (P<0.05), with the average colony number of 157.00+/-17.00/500 cells vs 110.00+/-12.90/500 cells of HL-60/neo cells. Less apoptotic cells were identified among HL-60/VEGF(165) cells than in HL-60/neo cells in the same culture condition. CONCLUSION: Autocrine VEGF plays an important role in the proliferation and apoptosis of acute myeloid leukemia cells.

Apoptosis↗

PubMed2003

[Modified FLAG regimen in the management of refractory acute myeloid leukemia].

OBJECTIVE: To evaluate the therapeutic effect of modified FLAG regimen in the management of refractory acute myeloid leukemia (AML). METHODS: Sixteen patients with refractory AML were divided into two groups. In modified FLAG regimen group (n=10), the patients received fludarabine (Flu, 50 mg/d, VDx5 d) and Ara-c (200 mg/d, VDx5 or 7 d). The regimen for classic FLAG group (n=6) consisted of Flu (50 mg/d, VDx5d), Ara-C (500 or 1,000 mg/d, VDx5d) and G-CSF (300 microg/d, x5 d, subcutaneously injected 4-6 hours before chemotherapy). Each patient received subcutaneous G-CSF (300 microg/d) when the white blood cell count was lower than 1.0x10(9)/L till the condition was corrected. RESULTS: The total complete remission(CR) rate of the 16 patients was 50% (8/16). Seven patients in modified group achieved CR (70%) and only one of the classic group did (17%, P<0.05). Episodes of infections were lower in modified group than in the classic group (50% vs 83%). CONCLUSION: Modified FLAG regimen is more likely than classic FLAG regimen to achieve CR and reduce infections in patients with refractory AML.

Adolescent↗

PubMed2003

[Effect of erythrocyte preserved for different lengths of time on anti-D antibody identification with three blood matching tests].

The specificity of the antigens and length of preservation time of erythrocytes are the interfering factors in blood group serological tests. In order to clarify the influence of preservation time of erythrocytes on the blood matching test, the titers of anti-D antibody were detected with papain method, BioVue cross matching card and DianaGel cross matching card in 7 series of panel red blood cells preserved for various length of time (0 to 9 months). The results showed that the titer of micro-column gel test (DianaGel card) was one tube higher than that of column agglutinating test (BioVue card). The titer of erythrocytes preserved for 9 months was as high as 256 tested by DianaGel card, but it was only 2 by papain method in the same anti-serum. It is suggested that there was no obvious difference between the results of micro-column gel test and column agglutinating test, and titer of papain method was the lowest.

Blood Grouping and Crossmatching↗

PubMed2003

[Quadruple therapy with CsA, MTX, MMF and ATG for preventing graft-versus-host disease in unrelated donor hematopoietic stem cell transplantation].

OBJECTIVE: To evaluate the efficacy of quadruple therapy with cyclosporine (CsA), methotrexate (MTX), mycophenolate mofetil (MMF) and low-dose antithymocyte globulin (ATG) for graft-versus-host disease (GVHD) prophylaxis in unrelated donor hematopoietic stem cell transplantation (URD-HSCT). METHODS: Thirteen patients with leukemia received URD-HSCT, of whom 11 had HLA genotypes and 2 had mismatch for 1 genetic locus. Another 11 leukemia patients all serologically matched underwent related donor (RD)-HSCT. Total body irradiation (TBI) plus cyclophosphamide (CTX) was adopted in 19 cases and modified BuCY conditioning regimen (hydroxyurea, busulfan, Ara-C, Cyclophosphamide ) in the other 5 cases. All the patients received CsA+MTX protocal for GVHD prophylaxis, and in those undergoing URD-HSCT, additional MMF and low-dose ATG were used. RESULTS: The incidence and severity of regimen-related toxicity differed little between unrelated and related transplantation. Acute GVHD (aGVHD) occurred in 46.2% of the patients undergoing URD- HSCT and in 55.6% of those with RD-HSCT, respectively. Four patients had chronic GVHD (cGVHD), in the 7 ones who could be followed up after URD-HSCT; 6 of the 9 patients with RD-HSCT developed cGVHD postoperatively. One patient with URD-HSCT died of hemorrhagic cystitis and another with RD-HSCT died of cytomegalovirus (CMV) pneumonia. The at one-year disease-free survival rate was 87.5% and 90.9% in patients with unrelated and related transplantation respectively. Significant difference was not noted in the positivity rate of CMV antigen between the patients receiving URD-HSCT or RD-HSCT. CONCLUSION: CsA+MTX in combination with MMF and low-dose ATG may decrease the incidence and severity of aGVHD without increasing transplant-related mortality or CMV infection.

Adolescent↗

PubMed2003

[Autogeneic peripheral blood hemopoietic stem cell transplantation for chronic myeloid leukemia with imatinib mesylate-induced negative Philadelphia chromosome].

OBJECTIVE: To study the possibility of curing chronic myeloid leukemia with autogeneic hemopoietic stem cell transplantation in patients with negative Philadelphia (Ph) chromosome induced by imatinib mesylate (STI 571) treatment. METHODS: Two patients with chronic myeloid leukemia in chronic phase, who had 90% Ph chromosome-positive cells and bcr/abl fusion gene-positive cells as shown by interphase fluorescence in situ hybridization (I-FISH), failed to respond favorably to interferon-alpha therapy in the treatment courses of 7 and 8 months, respectively. Treatment with STI 571 at a daily dose of 300 to 400 mg for 5 months to 8 months was subsequently implemented, after which the Ph chromosome and bcr/abl fusion genes became normal in detection for 3 times. Peripheral blood haemopoietic stem cell mobilization was then initiated by intravenous injection of cytarabine (2.0 g/d) for 3 days, etoposide (0.2 g/d) for 3 d and cyclophosphamide (1.0 g/d) for one day. When the white blood cell was below 1.0x10(9)/L, the G-CSF (300 microg/d) was administered subcutaneously for 5 or 6 d, and the peripheral blood mononuclear cells were collected by CS3000 Plus blood cell separator. The percentage of bcr/abl fusion gene-positive cells among CD34(9) cells enriched by MiniMAC ranged from 11% to 14%. After 3 or 4 weeks, the patients received total body irradiation at 9 Gy given in 2 fractions, with intravenous injection of cyclophosphamide (60 mg/kg daily) and etoposide (300 mg/d) for 2 d. On the day of transplantation, the collected mononuclear cells were 4.17x10(8)/kg and 3.9x10(8)/kg, with CD34(+)/ cells reaching 4.89x10(6)/kg.b.w and 4.89x10(6)/kg. CsA was also used since day -1 to day +13 of the transplantation for prevention of graft-versus-host disease. G-CSF was administrated daily at the dose of 300 microg subcutaneously from day +3 to +12. RESULTS: After the transplantation, the absolute neutrophil count (ANC) took a mean of 11 d to exceed 0.5x10(9)/L in these two patients, and 19 and 21 d, respectively, were needed for the platelet count to exceed 20x10(9)/L. The two patients showed cytogenetic relapse at 120 and 300 d after the transplantation, respectively. CONCLUSION: Autogeneic peripheral blood stem cells transplantation after Ph chromosome is negative in patients with chronic myeloid leukemia, who receive STI 571 treatment, may also relapse, and more radical elimination of Ph chromosome-positive cells is needed.

Adult↗

PubMed2003

[Induction of aGVHD after allogeneic hematopoietic stem cell transplantation for refractory or relapsed acute leukemia].

BACKGROUND & OBJECTIVE: Patients with refractory or relapsed acute leukemia after allogeneic hematopoietic stem cell transplantation had a poor prognosis with high death rate due to relapse or transplant-related mortality (TRM). The purpose of this paper was to clarify the role of inducing acute graft-versus-host disease (aGVHD) during transplantation in preventing relapse. METHODS: Thirty adult patients with refractory or relapsed leukemia were acute lymphoblastic leukemia (n=16), acute myelogenous leukemia (n=10), and acute mixed leukemia (n=4). They were in first complete remission (n=4), second complete remission (n=9), partly remission (n=12), and non-response (n=5) at the time of transplantation. Patients underwent allogeneic peripheral blood stem cell transplantation (allo-PBSCT) from HLA-identical siblings (n=21), mismatched siblings donors (n=3), and allogeneic bone marrow transplantation (n=5) or allo-PBSCT (n=1) from unrelated HLA matched donors. All patients received myeloablative regimens for eliminating residual leukemic cell. For aGVHD prophylaxis the patients with HLA-identical siblings donors received cyclosporine (CSA) alone, and the patients with mismatched siblings or unrelated donors received CSA, methotrexate, mycophenolate mofetil, and low-dose ATG. For inducing aGVHD after transplantation, patients were scheduled to be quickly reduced the maintenance dose of CSA at 20% to 30% off every week or treated with pre-emptive donor leukocyte infusion if there was no appearance of aGVHD at +30 days to 60 days after transplantation. RESULTS: After a median follow-up of 18.1 months, there were 24/30 (80%) patients developed aGVHD (grade 3 or 4 had 4/30, 13.3%). There were 11/19 (57.9%) patients developed chronic GVHD (cGVHD), with 3/19 (15.8%) had extensive cGVHD. Eighteen patients are alive with disease-free survival (18/30, 60%) and 12 patients have died of relapse (5/28, 17.9%) and TRM (7/30, 23.3%). CONCLUSION: Induction of aGVHD after transplantation is feasible and effective to prevent relapse in patients with refractory or relapsed acute leukemia.

Acute Disease↗

PubMed2002

[Expression of vascular endothelial growth factor in bone marrow cells of patients with acute myeloid leukemia].

OBJECTIVE: To investigate the role of vascular endothelial growth factor (VEGF) in the pathogenesis and progression of acute myeloid leukemia (AML). METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was employed for VEGF mRNA detection. VEGF levels in the bone marrow cell cultural supernatant and plasma from normal subjects and AML patients were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: VEGF mRNA expression was present in most of the AML cell lines HL-60, K562 and Raji, but not in Jurkat cells. The expression rate of VEGF mRNA in the bone marrow cells from AML patients (82%) was higher than the rates in normal subjects (30.76%) and AML patients with autologous bone marrow transplantation (41.67%). Refractory and non-refractory AML patients had higher mean plasma VEGF levels than the normal donors and AML patients with transplantation did, without significant differences observed in the latter 2 groups. With also significant difference between them, refractory and non-refractory AML groups had respectively 11.0 and 7.3-fold higher VEGF levels in the culture supernatant than the normal donor group did. CONCLUSION: The abnormality of VEGF expression may play an important role in the development of AML, and VEGF expression might be used as one of the indexes for prognostic assessment for AML patients.

Acute Disease↗

PubMed2002

[Transplantation of purified CD34+ stem cells from autologous peripheral blood for treatment of systemic lupus erythematosus].

We used the transplantation of purified autologous peripheral blood CD34+ stem cells to treat a 16-year-old female patient with systemic lupus erythematosus (SLE), who had received unsuccessful treatment with steroids and immunosuppressants, and has achieved satisfactory therapeutic effect. The diagnosis of SLE was established one year ago, and the patient had SLE Disease Activity Index (SLEDAI) of 21 on admission. After ineffective treatment with dexamethasone and cyclophosphamid (CTX) for 3 months, purified autologous peripheral blood CD34+ stem cell transplantation was adopted. Autologous peripheral hematopoietic stem cells were mobilized by intravenous injection of 2.0 g/d cyclophosphamid (CTX) for 3 d and subcutaneous injection of granulocyte colony-stimulating factor (G-CSF, 300 microgram/d). A CS-3000 plus blood cell separator was used to collect peripheral blood stem cells, and cell count of mononuclear cells and CD34+ stem cells and epitope analysis of T and B lymphocytes were performed by FACscan flow cytometry. After purification with CliniMACS, the number of CD34+ stem cells reached 15.13x106/kg, while that of CD3+ cells were only 1.35x105/kg. Pretreatment of the patient consisted of intravenous injection of (50 mg/kg each day)for 4 consecutive days and antithymocyte globulin (ATG, 2.5 mg/kg each day) for 3 consecutive days with methylprednisolone (MP) at the dose of 1.0 g on the first day and 0.5 g on the following 2 days. The granulocytes were recovered by G-CSF stimulation. The purified CD34+ stem cells (60 ml) were reinfused within 24 h after pretreatment, following which changes in clinical manifestations and immunologic markers were compared with those before the transplantation. Clinical and immunologic remissions were achieved after transplantation, with all the autoantibodies reversed to the negative, suggesting the short-term effectiveness of this therapy. Based on this observation, we conclude that this therapy is possible to effect an eventual cure of SLE in this case, but the long-term effect needs to be further observed in the follow-up study.

Adolescent↗