Biomedical subjects

C Fan

Publications and source records attributed to C Fan.

At least 55 records · Page 3Linked to original sources

PubMed2000

[Methodological study on preparation of a novel myocardial perfusion imaging agent: 99mTc-Q3].

This study was intended to explore the methods of preparing technetium-99m-N, N'-ethylenebis (acetylacetoneiminato) bis [tris (3-methoxy-1-propyl) phosphine] (99mTc-Q3) as a newer cationic myocardial perfusion imaging agent. The optimum scheme of technetium labeling on the basis of exploring the effects of differently labeled conditions on radiochemical purity was established by a multivariate orthogonal experimental design. A newer agent for myocardial perfusion imaging was developed based on the optimum scheme by a stannous chloride reduction method. Preparation, separation, purification and quality control were performed by a chromatography. Experiments for stability (in vitro), sterility, apyrogen, safeness, and for imaging in animals were carried out. "A2B2C2" was chosen as the optimum scheme of this labeled complex. There each of A, B and C factors has significant effect on the radiochemical purity, and there is no one-class cross effect on the radiochemical purity between them. The labeling efficiency and radiochemical purity were measured over 99% labeled 10 min later (at R. T.). The stability (in vitro) was good and kept up to 4 hr or testing (range: 92%-99.37%). The prepared product was sterile, apyrogenic and safe. The scintigraphic imaging in rabbits demonstrated that the tracer accumulated early in the heart and the myocardial imaging displayed clearly up to 3 hr. The results of this methodological study demonstrate that not only high quality 99mTc-Q3 can be obtained but also a standardized procedure for labeling all kinds of 99mTc-agents can be set up, and on this basis, the one-step kit of 99mTc-Q3 may be developed.

Animals↗

PubMed2000

[Investigation on Schistosoma japonicum infection in rodents in Yunnan Province].

OBJECTIVE: To investigate the role of rodents in the transmission of schistosomiasis in endemic areas in Yunnan Province. METHODS: Kato-Katz method was used to study the infection rate of rodents, humans and domestic animals. RESULTS: The infection rate was 0.9% (32/3,411) for rodents, 15.6% (461/2,964) for humans, and 9.6% (239/2,482), for domestic animals. The EPG(mean) was 5.8 for rodents, 1.8 for humans, 0.1 for cattle, 0.1 for horses and 0.02 for pigs. CONCLUSION: The rodents played a minor role in the transmission of schistosomiasis in the plateau area of Yunnan province.

Adolescent↗

PubMed1999

3-(Diethoxyphosphoryloxy)-1,2,3-benzotriazin-4(3H)-one (DEPBT): a new coupling reagent with remarkable resistance to racemization.

[formula: see text] The new crystalline phosphate reagent 3-(diethoxyphosphoryloxy)-1,2,3-benzotriazin-4(3H)-one (DEPBT) mediates amide bond formation with a remarkable resistance to racemization. Comparative racemization studies were carried out and DEPBT proved to be superior to typical phosphonium and uronium coupling reagents. DEPBT is easily prepared and is exceedingly stable with a shelf life of months at room temperature. The advantageous properties of DEPBT render it a useful and unique addition to the arsenal of coupling reagents.

Amides↗

PubMed1999

Voltammetric response and determination of DNA with a silver electrode.

A current from DNA was obtained using a silver electrode with low overpotentials for the first time. Experimental results revealed that the voltammetric response of DNA was attributed to the redox reactions of purine bases. It was also shown that such a method provided a convenient and practical way to determine DNA. A linear dependence of the peak currents on ssDNA concentrations was observed in the range 0.5-2.5 microg/mL. The relative standard deviation was 3.5% for six successive determinations at 0.5 microg/mL. The detection limit was 50 ng/mL. Influence of the structure and the length of the nucleic acids on their electrochemical behavior was discussed. In view of the merits of the silver electrode, this technique might provide new possibilities for further electrochemical research and determination of nucleic acids.

Adenine↗

PubMed1999

Tumor necrosis factor-alpha-induced proliferation of human Mo7e leukemic cells occurs via activation of nuclear factor kappaB transcription factor.

Tumor necrosis factor-alpha (TNF-alpha) stimulates proliferation of Mo7e, CMK, HU-3, and M-MOK human leukemic cell lines. We report here the signal transduction pathway involved in TNF-alpha-induced Mo7e cell proliferation. Mo7e cells spontaneously die in the absence of growth factors, but treating the cells with interleukin (IL)-3, IL-6, thrombopoietin, granulocyte/macrophage colony-stimulating factor, or TNF-alpha promotes their survival and proliferation. Although most of these factors activate MAP kinase and Jun NH2-terminal kinase/signal transducer and activators of transcription signaling pathways, TNF-alpha fails to activate either pathway. When Mo7e cells were treated with TNF-alpha, nuclear factor kappaB (NF-kappaB) was activated transiently. The activated NF-kappaB consisted of heterodimers of p65 and p50 subunits. The degradation of IkappaBalpha coincided with activation of NF-kappaB in TNF-alpha-treated cells. To investigate the role of activated NF-kappaB in TNF-alpha-induced Mo7e proliferation, a cell-permeable peptide (SN50) carrying the nuclear localization sequence of p50 NF-kappaB was used to block nuclear translocation of activated NF-kappaB. Pretreating Mo7e cells with SN50 blocked TNF-alpha-induced nuclear translocation of NF-kappaB and inhibited TNF-alpha-induced Mo7e cell survival and proliferation. A mutant SN50 peptide did not affect TNF-alpha-induced Mo7e cell growth. SN50 had no effects on IL-3- or granulocyte/macrophage colony-stimulating factor-induced Mo7e cell proliferation. The results indicate that activation of NF-kappaB is involved in TNF-alpha-induced Mo7e cell survival and proliferation.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1999

Constitutive activation of the JAK2/STAT5 signal transduction pathway correlates with growth factor independence of megakaryocytic leukemic cell lines.

The factor-independent Dami/HEL and Meg-01 and factor-dependent Mo7e leukemic cell lines were used as models to investigate JAK/STAT signal transduction pathways in leukemic cell proliferation. Although Dami/HEL and Meg-01 cell proliferation in vitro was independent of and unresponsive to exogenous cytokines including granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), IL-6, thrombopoietin (TPO), and tumor necrosis factor-alpha (TNF-alpha), the growth of Mo7e cells was dependent on hematopoietic growth factors. When these cell lines were cultured in medium without cytokines, a constitutively activated STAT-like DNA-binding factor was detected in nuclear extracts from both Dami/HEL and Meg-01 cells. However, the STAT-like factor was not detectable in untreated Mo7e cells, but was activated transiently in Mo7e cells in response to cytokine treatments. The constitutively activated and cytokine-induced STAT-like DNA-binding factor in these three cell lines was identified as STAT5 by oligonucleotide competition gel mobility assays and by specific anti-STAT antibody gel supershift assays. Constitutive activation of JAK2 also was detected in the factor-independent cell lines, but not in Mo7e cells without cytokine exposure. Meg-01 cells express a p185 BCR/ABL oncogene, which may be responsible for the constitutive activation of STAT5. Dami/HEL cells do not express the BCR/ABL oncogene, but increased constitutive phosphorylation of Raf-1 oncoprotein was detected. In cytokine bioassays using growth factor-dependent Mo7e and TF-1 cells as targets, conditioned media from Dami/HEL and Meg-01 cells did not show stimulatory effects on cell proliferation. Our results indicate that the constitutive activation of JAK2/STAT5 correlates with the factor-independent growth of Dami/HEL and Meg-01 cells. The constitutive activation of JAK2/STAT5 in Dami/HEL cells is triggered by a mechanism other than autocrine cytokines or the BCR/ABL oncoprotein.

Cell Division↗

PubMed1999

Protein A tangential flow affinity membrane cartridge for extracorporeal immunoadsorption therapy.

Tangential flow affinity membrane cartridge (TFAMC) is a new model of immunoadsorption therapy for hemoperfusion. Recombinant Protein A was immobilized on the membrane cartridge through Schiff base formation for extracorporeal IgG and immune complex removal from blood. Flow characteristics, immunoadsorption capacity and biocompatibility of protein A TFAMC were studied. The results showed that the pressure drop increased with the increasing flow rate of water, plasma and blood, demonstrating reliable strength of membrane at high flow rate. The adsorption capacities of protein A TFAMC for IgG from human plasma and blood were measured. The cartridge with 139 mg protein A immobilized on the matrix (6 mg protein A/g dry matrix) adsorbed 553 mg IgG (23.8 mg IgG/g dry matrix) from human plasma and 499.4 mg IgG (21.5 mg IgG/g dry matrix) from human blood, respectively. The circulation time had a major influence on IgG adsorption capacity, but the flow rate had little influence. Experiments in vitro and in vivo confirmed that protein A TFAMC mainly adsorbed IgG and little of other plasma proteins, and that blood cell damage was negligible. The extracorporeal circulation system is safe and reliable.

Animals↗

PubMed1999

Therapeutic approaches for ischemia/reperfusion injury in the liver.

Organ injury caused by transient ischemia followed by reperfusion is associated with a number of clinically and environmentally induced conditions. Ischemia/reperfusion (I/R) conditions arise during surgical interventions such as organ transplantation and coronary bypass surgery, and in diseases such as stroke and cardiac infarct. The destructive effects of I/R arise from the acute generation of reactive oxygen species subsequent to reoxygenation, which inflict direct tissue damage and initiate a cascade of deleterious cellular responses leading to inflammation, cell death, and organ failure. This review summarizes existing and potential approaches for treatment that have been developed from research using model systems of I/R injury. Although I/R injury in the liver is emphasized, other organ systems share similar pathophysiological mechanisms and therapeutic approaches. We also review current knowledge of the molecular events controlling cellular responses to I/R injury, such as activation of AP-1 and NF-kappaB pathways. Therapeutic strategies aimed at ameliorating I/R damage are focused both on controlling ROS generated at the time of oxygen reperfusion and on intervening in the activated signal transduction cascades. Potential therapies include pharmacological treatment with small molecules, antibodies to cytokines, or free-radical scavenging enzymes, such as superoxide dismutase or catalase. Additionally, the use of gene therapy approaches may significantly contribute to the development of strategies aimed at inhibiting of I/R injury.

Animals↗

PubMed1999

A comparison of attitudes towards mental illness and knowledge of mental health services between Australian and Asian students.

The aim of this study was to investigate whether Asian immigrants in Australia differed from Anglo-Australians in terms of attitudes towards mental illness, and knowledge of mental health services. A questionnaire was administered to 140 university students, including 63 Anglo-Australian students, 47 Asian students, and 30 students from European backgrounds. The results showed that there was a significant ethnic difference in terms of attitudes towards mental illness, and knowledge of mental health services. Furthermore, Asians who spoke a language other than English at home knew less about services for acute mental illness.

Acute Disease↗

PubMed1999

A comparison of the antifibrillatory effects of desethylamiodarone to amiodarone in a swine model.

We evaluated the effect of two different doses of desethylamiodarone (DEA) and amiodarone on the ventricular fibrillation threshold (VFT). We ascertained the VFT in 24 pigs randomized to intravenous DEA, amiodarone, or vehicle. Ventricular fibrillation was induced by pacing the right ventricle by using a primary drive train at a cycle length of 270 ms for eight beats of 2-ms duration each. A secondary train of 20 pulses of 4-ms duration (100 Hz) immediately followed this over a total duration of 200 ms synchronized to the primary drive train. The intensity of the secondary train stimuli current was initially 2 mA and was increased by 2-mA increments until sustained VF with hemodynamic collapse was induced. The minimal current strength needed to induce sustained VF was defined as the VFT measured in mA. DEA (10 mg/kg) increased the VFT significantly over baseline from 13.5+/-4.9 to 23.2+/-8.8 mA (p = 0.0076). Amiodarone, 10 mg/kg, increased the VFT significantly over baseline (mean +/- SD) from 14.4+/-3.6 to 23.8+/-6.1 mA (p = 0.0016). An additional dose of amiodarone (15 mg/kg) increased the VFT to 38.5+/-15.9 mA, which is significantly greater than the VFT derived from lower-dose amiodarone (p = 0.046). We showed that DEA (10 mg/kg) has a similar antifibrillatory effect as 10 mg/kg of amiodarone. We also demonstrated a dose-dependent effect on VFT for amiodarone.

Amiodarone↗

PubMed1999

The effect of amiodarone on the ventricular fibrillation threshold.

We evaluated the antifibrillatory effect of two different doses of amiodarone after cardiac arrest with a cardiopulmonary resuscitation (CPR) model in 19 pigs. Ventricular fibrillation was induced by pacing the right ventricle using a primary drive train at a cycle length of 270 msec for 8 beats. The minimum current strength necessary to induce sustained ventricular fibrillation was defined as the ventricular fibrillation threshold (VFT) measured in mA. Three VFT determinations were made at baseline, followed by 9 minutes of continuous CPR with two determinations of VFT, and three after stabilization. The pigs were placed into one of three groups: amiodarone 2 or 5 mg/kg, or placebo. The average poststabilization VFT in each group was compared with the average baseline VFT. Pigs receiving amiodarone 2 mg/kg had significantly higher VFT after stabilization than at baseline (22.88+/-12.76 to 27.10+/-10.18 mA, p=0.048), as did those receiving 5 mg/kg (17.03+/-7.01 to 28.08+/-11.58 mA, p=0.002). The deltaVFT was significantly greater with amiodarone 5 mg/kg than with vehicle (placebo), but not with 2 mg/kg. There were no changes in VFT in any group during CPR versus baseline. When active treatments were combined, the trend was toward better survival in the amiodarone groups (13/13) compared with the placebo group (4/6, p=0.076).

Amiodarone↗

PubMed1999

[The changes in arteriography in extremities sustaining high tension electric injuries].

OBJECTIVE: Because it is difficult to estimate the extent and degree of damage to the blood vessels of extremities sustaining high tension electrical injuries, arteriography was carried out to evaluate the vascular changes. METHODS: Selective arteriography was carried out 29 times for 26 extremities in 17 patients suffering from > 380 V electrical injuries. RESULTS: The arteriography showed that the injured arteries were narrowed and occluded, and vascular branches decreased or disappeared. Recanalization of the partially occluded arteries or collateral circulation formation was found after decompression. CONCLUSION: Arteriography is valuable to evaluate the vascular changes in high tension electrical injuries of extremities.

Adolescent↗

PubMed1999

[Studies on ACE gene insertion/deletion polymorphism, serum ACE activity, and diabetic retinopathy in type II diabetic patients].

To clarify the relationship among angiotensin 1-converting enzyme(ACE) gene insertion/deletion(I/D) polymorphism, serum ACE activity, and diabetic retinopathy in Type II diabetic patients, we examined 36 healthy controls, 40 Type II diabetic patients without diabetic retinopathy, and 68 Type II diabetic patients with diabetic retinopathy. All of patients suffered from Type II diabetes beyond 5 years and matched in age and body mass index. An insertion/deletion polymorphism of ACE gene was identified by polymerase chain reaction(PCR). Serum ACE activity was determined using spectrophotometry. The distribution of DD, ID, and II genotypes of the ACE gene did not differ among the three groups (16.7%, 33.3%, and 50.0% in the healthy controls; 22.5%, 35.0%, and 42.5% in Type II diabetic patients patients without diabetic retinopathy; and 20.6%, 30.9%, and 48.5% in Type II diabetic patients with diabetic retinopathy; respectively). The frequency of ACE I/D genotypes was not significantly different between non-proliferative retinopathy and proliferative retinopathy of Type II diabetic patients with diabetic retinopathy (P > 0.05). Serum ACE activity of three groups was similar (P > 0.05). These results do not support the hypothesis that the DD genotype of the ACE gene would be a clinically useful genetic marker for predicting the development of diabetic retinopathy in Type II diabetic patients. There is no association between ACE gene I/D polymorphism and the prognosis of diabetic retinopathy in Type II diabetic patients. ACE may not involve in forming diabetic retinopathy in Type II diabetic patients.

Adult↗

PubMed1999

[Relationship between serum angiotensin I-converting enzyme activity and diabetic nephropathy in patients with type II diabetes].

To clarify the relationship between serum angiotensin I-converting enzyme (ACE) activity and Type II diabetic patients with or without diabetic nephropathy. We examined 36 healthy controls, 58 Type II diabetic patients without diabetic nephropathy, and 50 Type II diabetic with diabetic nephropathy. The diabetic duration of all of Type II diabetic patients was more than 5 years. All patients matched well in age and BMI. An insertion/deletion polymorphism of ACE gene was identified by polymerase chain reaction(PCR). Serum ACE activity was determined using spectrophotometry. Although the distribution of DD, ID, and II genotypes of the ACE gene did not differ among the three groups, serum ACE activity was significantly higher in Type II diabetic patients with diabetic nephropathy than in that without diabetic nephropathy(P < 0.05), especially in the groups with D allele of ACE gene. Serum ACE activity had no difference between healthy controls and Type II diabetic patients without diabetic nephropathy. There is no association between serum ACE activity and Type II diabetic patients without diabetic nephropathy in any genotype of ACE gene. The increasing serum ACE activity plays a role in the initiation of diabetic nephropathy or may serve as a risk marker for later development of overt diabetic nephropathy in Type II diabetic patients.

Adult↗

PubMed1999

[A study on major chemical components of Uvaria grandiflora].

OBJECTIVE: To make clear the chemical constituents of Uvaria grandiflora (Annonaceae). METHODS: Purification was performed using sephadex LH-20 permeation and silica gel chromatography. Structures of the purified components were determined on the basis of 1H, 13C NMR analysis and also by comparison with those of authentic compounds. RESULTS: Two major triterpenes, suberosol and lupeol, were identified. CONCLUSION: This paper is the first report on the identification of suberosol and lupeol from the gunus Uvaria.

Pentacyclic Triterpenes↗

PubMed1999

[Studies on Chinese drugs zhiqiao and zhishi origin investigation and merchandise identification].

OBJECTIVE: To sort out the main original plants of Chinese drugs Zhiqiao and Zhishi. METHOD: Investigating the medicinal plant resources in the growing area and conducting morphological identification of more than 40 pieces of these two commercial drugs. RESULT: A taxonomic table, a distribution table and a commercial drug identification table are given. CONVLUSION: The Chinese medicinal plants Zhiqiao and Zhishi originated from Citrus aurantium and its varieties C. aurantium "Xiucheng", C. aurantium "Xiangcheng" and Poncirus trifoliata x C. aurantium, some other plants from Citrus genus and Poncirus trifoliata are taken as the origin of Zhiqiao and Zhishi only in a few areas.

China↗

PubMed1999

[Protein A tangential flow membrane chromatographic column used for immunoadsorption therapy].

Tangential flow membrane chromatographic column is a new model of immunoadsorption therapy from blood. The results showed that the structure of the column and the flowing channel had a little damages for blood cells. The relation of flow-rate and backpressure with water, plasma and blood individually as the fluid flowing through the column has been studied. It was observed that backpressures increased with fluid viscosity, when flow-rate of blood was 120 mL/min and the backpressure reached 0.093 MPa; The adsorption capacity of protein A of the column for IgG from human plasma has been measured. When plasma and blood individually circulated through the column for 1 h, the column with 139 mg protein A immobilized on the matrix (6 mg protein A/g dry matrix) adsorbed 553 mg IgG (23.8 mg IgG/g dry matrix) from human plasma and 499.4 mg IgG (21.5 mg IgG/g dry matrix) from human blood respectively. The circulation time had a great influence on IgG adsorption capacity; but the circulation rate had a little influence on IgG adsorption capacity. The result of extracoporeal blood perfusion for dog showed that the Protein A column has good blood biocompatibility.

Chromatography↗

PubMed1999

[Expression of genes aroG and pheA in phenylalanine biosynthesis].

aroG and pheA genes, encoding 3-Deoxy-D-arabinoheptulonate-7-phosphate synthase(DS) and Chorismate mutase (CM)-prephenate dehydratase(PD) in the pathway of phenylalanine biosynthesis respectively, were amplified by polymerase chain reaction(PCR). The genes were assembled on the multicopy vectors and expressed in both Escherichia coli and Brevibacterium. The products of two gene were detected by SDS-PAGE. The activities of relevant enzymes were measured in the crude extract of the host strain. When aroG-pheA genes were introduced into E. coli p2392, the activities of DS, CM and PD were increased by 4.3-fold, 4.4-fold and 2.2-fold respectively. Whereas in the case of Brevibacterium flavum 2732, the activities of DS, CM and PD were increased by 12.3-fold, 2.3-fold and 5.6-fold, respectively. As the results, the overproduction of phenylalanine was brought about by using the genetic engineering strain of B. flavum.

3-Deoxy-7-Phosphoheptulonate Synthase↗