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Biomedical subjects

K Xu

Publications and source records attributed to K Xu.

At least 127 records · Page 7Linked to original sources
PubMed1999

Morphology and composition of hydroxyapatite coatings prepared by hydrothermal treatment on electrodeposited brushite coatings.

Highly pure brushite (CaHPO4.2H2O) coatings on porous Ti6Al4V substrates were prepared by electrodeposition from aqueous electrolytes. The influence of hydrothermal treatment parameters on brushite-to-hydroxyapatite conversion and the morphology and phase composition of hydroxyapatite (HAP) coatings was studied. It was found that the content, Ca/P atomic ratio, grain size and pore size of HAP in coatings increase with increasing hydrothermal treatment temperature, and that increasing the pH value can promote brushite-to-HAP conversion and reduce the grain size of HAP. Under optimal conditions, highly pure HAP coatings with needle-like crystals and non-stoichiometric form, which are similar to those of calcium phosphate in human bone, can be obtained.

Journal Article↗
PubMed1999

Autologous endometrial co-culture in patients with repeated failures of implantation after in vitro fertilization-embryo transfer.

PURPOSE: Our purpose was to evaluate the effect of coculture on preembryo development and clinical outcome. METHODS: Enrolled patients underwent a luteal-phase endometrial biopsy. The tissue was then enzymatically digested (collagenase) and the stromal and glandular cells were separated by differential sedimentation rates. These cells were cultured to confluence, released, and then cryopreserved until the patient's in vitro fertilization (IVF)-embryo transfer (ET) cycle. All normally fertilized oocytes were then placed on the co-cultured cells until transfer on day 3. Preembryo development on co-culture was compared to that in the patient's noncocultured previous cycle. Implantation and clinical pregnancy rates were compared to those in a control group of patients undergoing IVF during the study period who were matched for age, stimulation protocol, number of oocytes retrieved, and preembryos transferred. RESULTS: Twenty-nine women underwent 31 cycles of IVF-ET. On day 3 the overall mean number of blastomeres per preembryo on co-culture compared to that in the patient's previous cycle was 6.3 +/- 1.8 vs. 5.6 +/- 1.2 (P = 0.04). The average percentage of cytoplasmic fragments on co-culture compared to the previous cycle was 16 +/- 9% vs. 19 +/- 9% (P = 0.32). At transfer, after preembryo selection, the mean number of blastomeres per preembryo on co-culture compared to that in the patient's previous cycle was 6.8 +/- 1.6 vs. 6.6 +/- 1.3 (P = 0.5). The implantation and clinical pregnancy rates between co-culture and the matched control group were 15% (14/93) vs. 13% (16/124) (P = 0.79) and 29% (9/31) vs. 25% (10/40) (P = 0.45). CONCLUSIONS: There was a significant improvement in the average number of blastomeres per preembryo on co-culture compared to that in the patient's previous noncoculture cycle. The overall implantation and clinical pregnancy rates between co-culture and a matched control group were not significantly different.

Adult↗
PubMed1999

Use of protamine to augment adenovirus-mediated cancer gene therapy.

Improving the therapeutic potential of adenoviral (Ad) suicide gene therapy has become an area of intense investigation since the inception of gene therapy strategies for cancer treatment. Poor efficiency of gene transfer to target tissues has become one of the most important limitations to Ad-based gene therapy. Since polycations have been shown to enhance adenovirus-mediated gene transfer in epithelial cells both in vitro and in vivo, we hypothesized that polycations could augment treatment efficacy in animals with established tumor. To address this hypothesis, protamine sulfate, a polycation already safely administered in humans, was complexed with a recombinant Ad (E1E3-deleted) vector containing the herpes simplex 1 thymidine kinase (HSVtk) suicide gene to treat cancer cell lines in vitro and in animals bearing intraperitoneal tumor. In the presence of 5 microg/ml protamine, the efficiency of gene transfer to a number of cancer cell lines normally resistant to adenovirus was significantly enhanced. Protamine's effect in vitro was found to be inversely proportional to the level of expression of the high affinity Ad binding site, coxsackievirus and adenovirus receptor (CAR), on the sur- face of the various cell lines tested. Ad.tk infected tumor cells were rendered 2.5- to three-fold more sensitive to 20 microM ganciclovir (GCV) in the presence of protamine. Protamine also augmented the in vivo transfer efficiency of the marker gene, LacZ (contained in an Ad vector), on the surface of tumors derived from an intraperitoneal mouse model. Quantitative imaging revealed 50% tumor surface transduced with LacZ when treatment was performed in the presence of 50 microg/ml protamine compared with 12% tumor surface in controls. However, experiments performed utilizing intraperitoneal administration of Ad.tk/GCV in the presence or absence of 50 microg/ml protamine demonstrated no significantly improved median survival in mice bearing established intraperitoneal tumors. Similarly, in Fischer rats bearing intrapleural tumor, no improvement in anti-tumor response was observed when Ad treatment was performed intrapleurally in the presence of protamine. Thus, although protamine induced an enhancement of Ad-mediated gene transfer in vitro and in vivo, its use as an adjunct to intracavitary Ad-based cancer gene therapy in vivo appears to be limited.

Adenoviridae↗
PubMed1999

Rayleigh-Bénard simulation using the gas-kinetic Bhatnagar-Gross-Krook scheme in the incompressible limit.

In this paper, a gas-kinetic Bhatnagar-Gross-Krook (BGK) model is constructed for the Rayleigh-Bénard thermal convection in the incompressible flow limit, where the flow field and temperature field are described by two coupled BGK models. Since the collision times in the corresponding BGK models can be different, the Prandtl number can be changed to any value instead of a fixed Pr=1 in the original BGK model [P. L. Bhatnagar, E. P. Gross, and M. Krook, Phys. Rev. 94, 511 (1954)]. The two-dimensional Rayleigh-Bénard thermal convection is studied and numerical results are compared with theoretical ones as well as other simulation results.

Journal Article↗
PubMed1999

Fenestration nodes and the wide submyelinic space form the basis for the unusually fast impulse conduction of shrimp myelinated axons.

Saltatory impulse conduction in invertebrates is rare and has only been found in a few giant nerve fibres, such as the pairs of medial giant fibres with a compact multilayered myelin sheath found in shrimps (Penaeus chinensis and Penaeus japonicus) and the median giant fibre with a loose multilayered myelin sheath found in the earthworm Lumbricus terrestris. Small regions of these nerve fibres are not covered by a myelin sheath and serve as functional nodes for saltatory conduction. Remarkably, shrimp giant nerve fibres have conduction speeds of more than 200 m s-1, making them among the fastest-conducting fibres recorded, even when compared with vertebrate myelinated fibres. A common nodal structure for saltatory conduction has recently been found in the myelinated nerve fibres of the nervous systems of at least six species of Penaeus shrimp, including P. chinensis and P. japonicus. This novel node consists of fenestrated openings that are regularly spaced in the myelin sheath and are designated as fenestration nodes. The myelinated nerve fibres of the Penaeus shrimp also speed impulse conduction by broadening the gap between the axon and the myelin sheath rather than by enlarging the axon diameter as in other invertebrates. In this review, we document and discuss some of the structural and functional characteristics of the myelinated nerve fibres of Penaeus shrimp: (1) the fenestration node, which enables saltatory conduction, (2) a new type of compact multilayered myelin sheath, (3) the unique microtubular sheath that tightly surrounds the axon, (4) the extraordinarily wide space present between the microtubular sheath and the myelin sheath and (5) the main factors contributing to the fastest impulse conduction velocity so far recorded in the Animal Kingdom.

Animals↗
PubMed1999

[Refractory anemia and preleukemia: an analysis of 92 cases].

OBJECTIVE: To investigate the relationship between MDS-RA (refractory anemia subtype of myelodysplastic syndromes) and preleukemia (PL). METHODS: Hematological parameters of 86 RA and 6 PL patients were retrospectively analyzed. RESULTS: Thirty-four RA cases (39.53%) transformed into acute leukemia (AL), RA with excess blasts (RAEB), or RAEB in transformation (RAEB-t). As compared with 52 non-transformed RA cases, the transformed cases showed the following hematological features: 1. higher frequencies of immature granulocytes (P < 0.005), erythroblasts (P < 0.05) and megaloerythrocytes (P < 0.05), and higher granulocyte nuclear lobulation (P < 0.001) in peripheral blood; 2. higher percentages of early erythroid and granulocytic lineages (P < 0.05), and higher frequencies of erythroblasts with multiple nuclei (P < 0.05), pseudo Pelger-Huet abnormality (P < 0.05), and micromegakaryocytes (P < 0.005) in bone marrow. CONCLUSION: There is a higher overlap between RA and PL; the above hematological features may be useful for predicting the transformation of RA patients. Based on those findings, a score system for predicting the transformation of RA was proposed.

Adolescent↗
PubMed1999

[Detection of alpha-thalassemia 1 gene among 142 beta-thalassemia gene carriers].

OBJECTIVE: To investigate the coincidental rate of double heterozygous state of beta-thalassemia and alpha-thalassemia 1 in Guangdong area. METHODS: One handred and forty-two DNA samples with beta-thalassemia trait were amplified by polymerase chain reaction(PCR) to detect alpha-thalassemia 1 gene. The positive cases were further detected by mutant primer PCR or by reverse dot blot hybridization (ASO/RDB) to confirm their beta-thalassmia mutations. RESULTS: Thirteen cases (9.15%) were identified to combine with alpha-thalassemia 1 gene. The mutant loci of beta-globin gene in these cases were that 5 were in CD 41-42 (-TCTT), 3 in IVS-2-654(C-->T), 2 in CD 17 (A-->T) and 3 in CD 71-72 (+A), CD 43(G-->T) and -28 (A-->G), respectively. CONCLUSIONS: The occurrence of this dual heterozygotes among beta-thalassemia trait is relatively frequent and it should be paid much attention to in genetic counselling and prenatal diagnosis of thalassemia in this area.

Adult↗
PubMed1999

[The combined use of scopolamine, naltrexone and naloxone as a rapid, safe and effective detoxification treatment for heroin addicts].

OBJECTIVE: To evaluate the efficacy of a rapid detoxification schedule for heroin addicts by scopolamine combined with opiate receptor antagonists. METHODS: The life signs such as temperature, blood pressure, ECG, heart rate, respiratory rate and blood oxygen saturation were monitored during the process of rapid detoxification treatment. The naloxone challenge test, withdrawal symptoms scale and naltrexone maintenance were used to evaluate the efficacy of the rapid detoxification. RESULTS: The withdrawal symptoms of 84 heroin addicts induced by naltrexone and naloxone were controlled completely under scopolamine administration in the 6-8 hours treatment period, although the naloxone challenge test was able to induce slight and transient withdrawal symptoms in the second day, and all patients were transferred rapidly to naltrexone maintenance. During treatment, the temperature in 19 cases elevated, and all patients showed increased heart rate, blood pressure and respiratory rate. However, the blood oxygen saturation was still stable after oral-administration of naltrexone and continuous injection of naloxone during the detoxification. Blood test in gastric fluid was positive in 3 cases during the detoxification. The follow-up data showed that the average maintenance time of naltrexone was 2.6 months, and the percentage of drug free was 21% in 6 months after the detoxification in 84 cases. CONCLUSION: The combined use of scopolamine, naltrexone and naloxone is a rapid, safe and effective detoxification treatment protocol for heroin addicts.

Adult↗
PubMed1999

Evi-1 and MDS1-Evi-1 genes in pathogenesis of myelodysplastic syndromes and post-MDS acute myeloid leukemia.

OBJECTIVE: To investigate expression of Evi-1 and MDS1-Evi-1 genes in myelodysplastic syndromes (MDS) and post-MDS acute myeloid leukemia (post-MDS AML), and its role in pathogenesis or progression of MDS and post-MDS AML. METHODS: Expression of Evi-1 and MDS1-Evi-1 genes was examined in 31 MDS, 11 post-MDS AML, and 34 de novo AML patients by a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Evi-1 expression was not detected in bone marrow samples of 8 normal controls, but low MDS1-Evi-1 expression levels (MDS1-Evi-1/GAPDH < 0.1) were detected in 3 of the 8 controls. Evi-1 RNA was expressed in 1 of 8 RA, 8 of 13 RAEB and 6 of 9 RAEB-T patients, and the percentage of Evi-1 expression in RAEB(T) patients was higher than that in RA (P < 0.05). MDS1-Evi-1 expression was detected in 5 of 8 RA, 9 of 13 RAEB and 5 of 9 RAEB-T patients, and MDS1-Evi-1 expression levels (MDS1-Evi-1/GAPDH > 0.1) were markedly higher than those in the controls. Evi-1 expression was gradually increased in 4 of 5 RAEB-T patients with transformation from MDS to AML. The percentages of Evi-1 and MDS1-Evi-1 expression in post-MDS AML patients were significantly (P < 0.01 and P < 0.05 respectively) higher than those in de novo AML. The colonies of hematopoietic progenitor cells were decreased in Evi-1 and MDS1-Evi-1-positive MDS patients as compared with those in Evi-1 and MDS1-Evi-1-negative patients. CONCLUSION: Abnormal expression of the Evi-1 gene and overexpression of MDS1-Evi-1 gene may play a role in the pathogenesis or progression of MDS and post-MDS AML.

Adult↗
PubMed1999

[Primary sarcoma of pulmonary artery: a case report].

OBJECTIVE: To call attention to the rare involvement of pulmonary artery by sarcoma. METHODS: To summarize the clinical, radiological and pathologic features of a case of pulmonary artery sarcoma. RESULTS: Pulmonary artery sarcoma has similar clinical manifestations as other pulmonary artery obstructive diseases (including pulmonary thromboembolism). The diagnosis should be considered in the patient with clinical presentations suggested pulmonary embolism. The radiological findings included unilateral hilar enlargement, contiguously soft tissue-filled pulmonary artery and pulmonary nodules and clinically deterioration was found after anticoagulant therapy. CONCLUSION: Pulmonary artery sarcoma is usually misdiagnosed as other pulmonary artery obstructive diseases. More attention should be paid to it.

Adult↗
PubMed1999

[The application of BTA stat in the diagnosis of bladder tumor and hematuria].

OBJECTIVE: To analyze the value of the Bard BTA Stat for the diagnosis of bladder tumor and hematuria in order to find a new, noninvasive examination method. METHODS: BTA Stat, an one step monoclonal antibody immunofluorescence analysis that qualitatively detects the presence of bladder tumor associated antigen (hCFHrp), was used. 65 patients with hematuria, 71 patients with bladder transitional cell carcinoma, and 10 normal people underwent voided urine BTA Stat analysis. RESULTS: The specificity of the technique for patients with bladder transitional cell carcinoma and hematuria was 84.6% and 31.1% respectively, with a sensitivity of 73.7% and 90.0% respectively. CONCLUSIONS: BTA Stat was considered a convenient, rapid and noninvasive method in the diagnosis of bladder tumor. However, the results were interfered by the presence of erythrocyte in urine, infection, urinary lithiasis. This method is proved to be useful in the surveillance of bladder tumor.

Adult↗
PubMed1999

[Early use of Chinese drug rhodiola compound for patients with post-trauma and inflammation in prevention of ALI/ARDS].

OBJECTIVE: To evaluate the effects of the Chinese drug rhodiola on the preventive treatment of acute lung injury (ALI) caused by post-traumatic/inflammatory and thoracic-cardiovascular operations. METHODS: 104 patients who coincide with their diagnosis and standard scale were divided randomly in to single number groups A(1), B(1), C(1) and D(1) (early preventive treatment group EG) and double number groups A(2), B(2), C(2) and D(2) (control group CG). The treatment of primary disease both in EG and CG was similar, but in EG four grams of rhodiola compound (RCO) were used every day for a period of 3-15 days since admission and 5-7 days after operation. The indicators related to ALI in each groups were measured. RESULTS: PaO(2), AaDO(2) and hemorheology were significant in EG than in CG (P < 0.05) or (P < 0.01). The complication rate of ARDS was decreased about of 50.0% in EG than in CG. CONCLUSIONS: Early use of RCO may protect against major risk factors of ALI/ARDS caused by massive trauma/infection and thoracic-cardio-operations.

Adolescent↗
PubMed1999

[Posttraumatic or inflammatory acute respiratory distress syndrome on high altitude area: a retrospective analysis of 94 deaths due to ARDS/MOF].

OBJECTIVE: To determine the characteristic predictors of acute respiratory distress syndrome (ARDS) in the high altitude area of China. METHODS: According to the diagnostic criteria of ARDS, 2 325 cases were screened in the recent 10 years. Except malignant tumors, cardio-cerebrovascular diseases, chronic obstructive pulmonary disease, and chronic multiple organ failure, the causes of death were analysed retrospectively. RESULTS: 94 cases (4.04%) were diagnosed as ARDS, but in the primary case record, only 27 cases (1.16%) had been diagnosed as ARDS/MOF. Of the 94 ARDS patients, 79 complicated by extrapulmonary organ damage involving the kidney, heart, liver, gastro-intestinal tract, and brain. A total of 305 organs were involved (average 3.24 organs each case). Lung failure only accounted for 15 cases. CONCLUSIONS: The combination of the diagnostic criteria of ARDS for high altitude area and flate area, injury severity scale, blood gas monitoring, and integrated traditional Chinese medicine and western medicine may improve the prognosis of ARDS.

Adolescent↗
PubMed1999

[Establishment of sandwich ELISA with McAbs to measure histidine-rich glycoprotein in plasma].

The objective of this paper is to establish a method using sandwich ELISA with McAbs to measure plasma histidine-rich glycoprotein (HRG). The results showed that this method, with a working range from 2.5 ng.ml-1 to 80 ng.ml-1, provided the lower limit of detection of 1 ng.ml-1, the average intra-assay CV, the interassay CV and the recovery rate of HRG were 8.2%, 11.5% and 89.1%, respectively. Interference by antithrombin III and human albumin was not significant. With this method, the concentration of plasma HRG from healthy donors was (110.3 +/- 9.7) mg.L-1, and the value of plasma HRG in liver cirrhosis was (79.5 +/- 12.6) mg.L-1. These results suggest that sandwich ELISA with McAbs is high sensitive, precise and specific.

Adult↗
PubMed1999

[The satisfaction, efficacy, and relative factors for Norplant in countryside of Sichuan].

A total of 1473 Norplant users in the countryside of Sichuan Province were investigated to present a multivariate analysis of satisfaction, side effect, and efficacy for Norplant. The results showed that contraceptive efficacy rate, continuation rate, prevalence rate of side effects and satisfactory rate were 99.3%, 90.6%, 86.4%, and 69.7%, respectively. The logistic regression analysis showed that the variables significantly contributing to satisfaction were the user's knowledge about Norplant, the user's voluntary choice of Norplant, and the spouse's satisfaction. The satisfaction was associated with continuation and the prevalence of side effects. It is concluded that Norplant is efficacious and satisfactory to a certain extent among the users in rural Sichuan; its continuation rate is high but the prevalence of side effects is noticeable. For the wide application of Norplant in the countryside, it is important to strengthen propagation and education.

Adult↗
PubMed1999

[Changes in computed tomogram in cerebral parenchymal cysticercosis treated with albendazole].

AIM: To observe the changes in cerebral computed tomogram (CT) in cerebral parenchymal cysticercosis after albendazole treatment. METHODS: Cerebral CT scanning was conducted in 57 patients with cerebral cysticercosis in our hospital before, during and after albendazole treatment. RESULTS: Cerebral CT might be normal before onchospheres became cysticercariae in the brain. Small cystic lesions could turn into other CT signs of cerebral cysticercosis after albendazole treatment. CONCLUSION: Normal cerebral CT cannot rule out the disease. Small cystic lesions are the earliest pathological and active signs of the disease. Nodular focus occurs after the death of Cysticercus and calcification is the final outcome of the disease.

Adolescent↗
PubMed1999

[The relation of fetal growth and the biological risk factors of coronary heart disease].

OBJECTIVE: To examine the relationship between fetal growth and the biological risk factors of coronary heart disease (CHD) in adult life in China. METHODS: Follow up stuty of 628 men and women who were singleton born during 1948-1954 whose birth size were measured in detail. RESULTS: Decreasing birth weight increased the probability of myocardial ischaemic symptom related to CHD (beta = -0.0018, P < 0.01). The Odds ratio (OR) related to hypertension increased with decreasing birth weight and ponderal index (PI, kg/m3). The OR were 5.9 in people whose PI were 24 kg/m3 or less compare to people whose PI were more than 28 kg/m3. The OR related to impaired glucose tolerance(IGT) also increased with decreasing birth weight and PI. Insulin resistance, represented by fast insulin, rose with decreasing birth weight and head circumference(for trend, all P < 0.01). Serum TG concentration significantly rose with decreasing birth weight, PI and head circumference (for trend, P < 0.01, P < 0.01, P < 0.05), while HDL-C rose with increasing birth weight and head circumference (for trend, P < 0.05, P < 0.01). All above mentioned relations between birth size and the level of risk factors during adulthood were independent of gestation and adult lifestyle. CONCLUSIONS: In China, low birth measurements which represent the fetal growth retardation might contribute to the present of biological risk factors of coronary heart disease during adulthood, such as hypertension, diabetes, insulin resistance, high serum triglyceride and low HDL-C.

Birth Weight↗