Biomedical subjects

C Fan

Publications and source records attributed to C Fan.

At least 37 records · Page 2Linked to original sources

PubMed2001

[The ultrastructure changes of nerve fibers in pressure side of periodontal ligament during orthodontic tooth movement in rats].

OBJECTIVE: To observe the ultrastructure changes of nerve fibers in pressure side of periodontal ligament during orthodontic tooth movement (OTM) in rats. METHODS: The left maxillary of fifteen rats molar was moved mesially by an appliance for 2 days, 1 week, 2 weeks and 3 weeks. The ultrastructure changes of nerve fibers in pressure side of the periodontal ligament in rats were observed with electron microscope. RESULTS: The thick myelinated axon was degenerated after 2 days of OTM and not recovered after 3 weeks of OTM; the number of thin unmyelinated axons was increased after 2 days of OTM. It reached a maximum after 1 week of OTM and recovered after 3 weeks of OTM. Only part of thin unmyelinated was slightly degenerated. At the same time, some of the thin myelinated axons were slightly degenerated and partly demyelinated. CONCLUSION: The nerve fibers were involved in periodontal tissue remodelling.

Animals↗

PubMed2001

[Experimental study on carcinogenic activity of the organic extracts from water of the sifangtai section of songhua river].

OBJECTIVES: To study the carcinogenic activity and potential mechanism of the organic extracts from the Songhua River in vitro. METHODS: The in vitro cell transformation and single cell gel electrophoresis (SCGE) tests were detected with the ether extracts of water. The expression of anticancer genes p53, p16, and p21 measured by immunohistochemical assays and the apoptosis by TUNEL assay were also studied. RESULTS: The extracts from the water induced malignant transformation of BALB/C mouse embryo fibroblast cells and induce DNA damage. p53, p16 and p21 failed to express in transformed cells induced by the water extracts, and the apoptosis rate of transformed cells decreased. CONCLUSION: This study demonstrates that the organic extracts from the Songhua River has potential carcinogenicity.

Animals↗

PubMed2001

[Effect of SP on intracellular free calcium concentration in cultured osteoblast].

OBJECTIVE: To investigate the effect of SP on intracellular free calcium concentration (Ca2+)i in cultured osteoblast. METHODS: Effect of SP on intracellular free calcium was measured using cell culturing and laser scanning confocal microscopy with fluo-3/AM as a fluorescence probe. RESULTS: After treated with SP(10(-4) mol/L), 70% of the cells responded to it; the intracellular (Ca2+)i increased markedly [fluorescence intensity increased by (90 +/- 18)%]. CONCLUSIONS: These results suggested that calcium may have a role as a intracellular secondary messenger in the action of SP in osteoblast.

Animals↗

PubMed2001

[A comparison between 99mTc-Q3 and 201Tl on clearance and retention properties at varying coronary flow rates in isolated rabbit heart].

OBJECTIVE: This study was intended to investigate and compare technetium-99m-N, N'-ethylenebis(acetylacetoneiminato)bis[tris (3-methoxy-1-propyl) phosphine] (99mTc-Q3) versus 201Tl on clearance and retention properties at varying coronary flow rates in isolated rabbit heart. METHODS: 20 New Zealand White rabbits were anaesthetized and excised through a median sternotomy. The hearts were isolated and arrested in ice-cold saline. The external perfusion models with isolated rabbit hearts were installed and were perfused at flow rates ranging from 0.52 to 3.75 ml/(g wet wt.min) in the absence of tracer recirculation. Furthermore, 99mTc-Q3 experimental relations between uptake, clearance and retention were explored in comparison with 201Tl. RESULTS: 201Tl net uptake was higher and also more affected by flow rates (P < 0.05) as compared with 99mTc-Q3 net uptake. 201Tl clearance was faster than 99mTc-Q3 clearance within 4 to 25 minutes after radiopharmaceuticals injection in high flow rates group, and 201Tl clearance was faster than 99mTc-Q3 clearance within 40 minutes after radiopharmaceuticals injection in low flow rates group. 201Tl earlier rapid clearance observed in the high flow rates group did not appear in the low flow rates group, but 99mTc-Q3 did not display early rapid clearance either in the high flow rates group or in the low flow rates group. CONCLUSION: Owing to faster clearance, the superiority of 201Tl over 99mTc-Q3 as a myocardial perfusion imaging agent would be lost entirely within 10 minutes after injection of agent, therefore 99mTc-Q3 is still a good myocardial perfusion imaging agent, and further study is worth doing.

Animals↗

PubMed2001

[99mTc-Q3 uptake property at varying coronary flow rates in isolated rabbit heart: comparison between 99mTc-Q3 and 201Tl].

OBJECTIVE: This experiment was designed to explore myocardial 99mTc-Q3 uptake property. METHODS: 20 New Zealand White rabbit heart perfusion models were prepared and the isolated rabbit hearts were perfused by double-radionuclide method at varying coronary flow rates from 0.52 to 3.75 ml/g wet wt/min using developed perfusion liquid with autoblood in comparison with 201Tl in the absence of tracers recirculation. RESULTS: Mean 99mTc-Q3 peak instantaneous uptake was lower(0.65 +/- 0.077) and more affected by low rates (P < 0.05) than 201Tl peak instantaneous uptake (0.82 +/- 0.07, P < 0.01). CONCLUSION: These data were interpreted to indicate: 1. 99mTc-Q3 is not as well extracted as 201Tl; 2. varying the coronary flow rate has significant effects on the uptake of 99mTc-Q3 and 201Tl; 3. similarly to 201Tl, the coronary blood flow conditions may be overestimated by the myocardial radioactive uptake acquired with low flow perfusion, but the coronary blood flow conditions may be underestimated by the myocardial radioactive uptake acquired with high flow perfusion. Further studies on retention and clearance of 99mTc-Q3 need to be conducted.

Animals↗

PubMed2000

Control of paroxysmal atrial fibrillation recurrence using combined administration of propafenone and quinidine.

The frequent recurrence of paroxysmal atrial fibrillation (PAF) despite the use of standard antiarrhythmic agents prompted the use of new therapeutic approaches. There are few data on systematic assessment of PAF control with stepwise dose escalation and the use of a drug combination. Low-dose quinidine may promote the efficacy of propafenone by inhibiting its degradation through the cytochrome P450 pathway (CYP2D6). We prescribed propafenone 300 to 450 mg/day to 60 patients with PAF for 8 weeks, and 62% were symptomatically controlled. The 19 refractory patients were randomized in a double-blinded fashion to receive either a higher dose of propafenone (450 to 675 mg/day) or the standard dose of propafenone with low-dose quinidine 150 mg/day, each for an 8-week study period, and subsequently crossed over to the alternative treatment. The resulting serum propafenone concentrations were 259 +/- 208 and 336 +/- 237 mg/day (p >0.5), respectively. Both treatment arms prolonged the time to the first symptomatic atrial fibrillation (AF) recurrence and the interval between attacks, and AF was controlled in 37% of patients. However, the higher dose of propafenone was associated with gastrointestinal side effects not present with the low-dose quinidine combination. Of the 10 refractory patients, 7 were further controlled with a standard dose of propafenone plus quinidine (600 mg/day). Overall, control of PAF was achieved in 85% of patients at the end of 8 months; adverse effects necessitating withdrawal were observed in 6%, and uncontrolled AF in 5% of patients. There was no difference in the mean AF rate during recurrences in all phases, and ventricular proarrhythmia was not seen. This study documents the role of stepwise antiarrhythmic treatment of PAF. The use of a standard dose of propafenone, followed by low-dose quinidine combination to reduce propafenone degradation, and the combined standard dose of propafenone and quinidine may be used to maximize efficacy and tolerability.

Adolescent↗

PubMed2000

Independent adaptation to riverine habitats allowed survival of ancient cetacean lineages.

The four species of "river dolphins" are associated with six separate great river systems on three subcontinents and have been grouped for more than a century into a single taxon based on their similar appearance. However, several morphologists recently questioned the monophyly of that group. By using phylogenetic analyses of nucleotide sequences from three mitochondrial and two nuclear genes, we demonstrate with statistical significance that extant river dolphins are not monophyletic and suggest that they are relict species whose adaptation to riverine habitats incidentally insured their survival against major environmental changes in the marine ecosystem or the emergence of Delphinidae.

Adaptation, Physiological↗

PubMed2000

Linkage of familial amyotrophic lateral sclerosis with frontotemporal dementia to chromosome 9q21-q22.

CONTEXT: Occasionally, 2 or more major neurodegenerative diseases arise simultaneously. An understanding of the genetic bases of combined disorders, such as amyotrophic lateral sclerosis (ALS) with frontotemporal dementia (FTD), will likely provide insight into mechanisms of these and related neurodegenerative diseases. OBJECTIVE: To identify loci that contain genes whose defects cause ALS. DESIGN: A genome-wide linkage analysis of 2 data sets from an ongoing study begun in the mid-1980s at 4 university research centers. SUBJECTS: An initial subset of 16 families (549 people) potentially informative for genetic analysis, in which 2 or more individuals were diagnosed as having ALS, identified from a Boston data set of 400 families and 4 families potentially informative (244 people) subsequently identified from a Chicago data set of more than 300 families to test a hypothesis based on findings from the Boston families. MAIN OUTCOME MEASURES: Linkage calculations assuming autosomal dominant inheritance with age-dependent penetrance (a parametric logarithm-of-odds [lod] score of 1.0 or greater required for further study of a potential locus); crossover analysis involving the ALS-FTD locus. RESULTS: In a set of families in which persons develop both ALS and FTD or either ALS or FTD alone, a genetic locus that is linked to ALS with FTD located between markers D9S301 and D9S167 was identified on human chromosome 9q21-q22. Families with ALS alone did not show linkage to this locus. Crossover analysis indicates this region covers approximately 17 cM. CONCLUSION: These data suggest that a defective gene located in the chromosome 9q21-q22 region may be linked to ALS with FTD. JAMA. 2000;284:1664-1669.

Aged↗

PubMed2000

Activation of p38 mitogen-activated protein kinase is required for tumor necrosis factor-alpha -supported proliferation of leukemia and lymphoma cell lines.

To elucidate mechanisms of tumor necrosis factor alpha (TNF-alpha)-induced proliferation of a number of human leukemia and lymphoma cell lines, we examined the role of p38 mitogen-activated protein kinase (MAPK) in TNF-alpha signaling in Mo7e and Hut-78 cells. TNF-alpha-dependent p38 MAPK activation was detected in both Mo7e and Hut-78 cells and was blocked by the p38 MAPK inhibitor, SB203580. Ablation of p38 MAPK activity by SB203580 abrogated TNF-alpha-induced Mo7e cell proliferation and TNF-alpha-dependent autocrine growth of Hut-78. As we have shown previously that activation of the nuclear factor kappaB (NF-kappaB) is also required for TNF-alpha-induced Mo7e cell proliferation, the involvement of p38 MAPK in NF-kappaB activation was assessed. SB203580 did not affect TNF-alpha-signaled nuclear translocation and DNA-binding activity of NF-kappaB, and inhibition of NF-kappaB function did not affect TNF-alpha-induced p38 MAPK activation, indicating that these events are not dependent on each other. However, SB203580 depressed the expression of NF-kappaB-dependent genes, as monitored by a kappaB-driven reporter gene. Our findings demonstrate that activation of both p38 MAPK and NF-kappaB plays a critical role in TNF-alpha-mediated survival and proliferation of human leukemia and lymphoma cells, and p38 MAPK acts at least in part by facilitating the transcriptional activation function of NF-kappaB.

Cell Division↗

PubMed2000

Recombinant Escherichia coli cell for d-p-hydroxyphenylglycine production from d-N-carbamoyl-p-hydroxyphenylglycine.

Recombinant Escherichia coli cell containing D-amidohydrolase was employed to convert D-N-carbamoyl-p-hydroxyphenylglycine (D-CpHPG) to D-p-hydroxyphenylglycine (D-pHPG). Biotransformations under pH 7 and 40 degrees C allowed to complete conversion of D-CpHPG into D-pHPG. Under the same reaction pH, the D-amidohydrolase activity of the cell in the phosphate buffer was higher than that in the Tris buffer. The activity decreased with the increase of phosphate buffer concentration. Instead of using buffer, the reaction pH maintained constant at 7 by titrating with 1 N HCl resulted in a higher D-pHPG production rate. Flocculating the cell suspension with chitosan and cross-linked by glutaraldehyde made the cell recovery for repeated use much easier. Both the cross-linking and (PMSF; a protease inhibitor) treatments could increase the cell reusability and storage stability. However, the cross-linking decreased the D-amidohydrolase activity of the cell to about 50%. The D-amidohydrolase activities of free and cross-linked cell were inhibited at substrate concentration higher than 150 mM and 100 mM, respectively. The conversion of 150 mM D-CpHPG to D-pHPG could be completed within 7 h for the free cell at the concentration of 10% (wet weight/volume).

Journal Article↗

PubMed2000

Members of the bHLH-PAS family regulate Shh transcription in forebrain regions of the mouse CNS.

The secreted protein sonic hedgehog (Shh) is required to establish patterns of cellular growth and differentiation within ventral regions of the developing CNS. The expression of Shh in the two tissue sources responsible for this activity, the axial mesoderm and the ventral midline of the neural tube, is regulated along the anteroposterior neuraxis. Separate cis-acting regulatory sequences have been identified which direct Shh expression to distinct regions of the neural tube, supporting the view that multiple genes are involved in activating Shh transcription along the length of the CNS. We show here that the activity of one Shh enhancer, which directs reporter expression to portions of the ventral midbrain and diencephalon, overlaps both temporally and spatially with the expression of Sim2. Sim2 encodes a basic helix-loop-helix (bHLH-PAS) PAS domain containing transcriptional regulator whose Drosophila homolog, single-minded, is a master regulator of ventral midline development. Both vertebrate and invertebrate Sim family members were found sufficient for the activation of the Shh reporter as well as endogenous Shh mRNA. Although Shh expression is maintained in Sim2(-)(/)(-) embryos, it was determined to be absent from the rostral midbrain and caudal diencephalon of embryos carrying a dominant-negative transgene that disrupts the function of bHLH-PAS proteins. Together, these results suggest that bHLH-PAS family members are required for the regulation of Shh transcription within aspects of the ventral midbrain and diencephalon.

Animals↗

PubMed2000

Assessment of the drug interaction between alteplase and nitroglycerin: an in vitro study.

Alteplase is the most commonly administered thrombolytic agent in the United States. However, concurrent therapy with nitroglycerin reduces plasma alteplase concentrations and its clinical efficacy. We sought to determine if this interaction is concentration and pH dependent. Seventy plasma samples were prepared and divided into three groups: alteplase 500 IU/ml alone (group 1), alteplase 500 IU/ml plus nitroglycerin 5 ng/ml (group 2), and alteplase 500 IU/ml plus nitroglycerin 200 ng/ml (group 3). The samples were analyzed at time zero and 3 hours (incubated at 37 degrees C). Group 1 had significantly higher plasma alteplase concentrations than group 3 (p<0.001). When alteplase and nitroglycerin are combined, the degradation of alteplase in plasma is enhanced.

Data Interpretation, Statistical↗

PubMed2000

An evaluation of the hemostatic effect of externally applied notoginseng and notoginseng total saponins.

No effective hemostatic agents are available for external use. This project was conducted to evaluate the hemostatic effects of notoginseng using a hemorrhagic rat model. Rats (n = 40) were divided into four groups, and their tails were transected 5 mm from the tip. Group 1 received no treatment (control), while the other groups received external powder applied to the wound. Group 2 received placebo (flour), group 3 received ground notoginseng, and group 4 received a saponin extract of notoginseng. The total bleeding time was determined and compared between groups. The notoginseng group had lower bleeding times (9.60 +/- 1.50 min) than the control group (19.23 +/- 4.09 min, p < 0.001) or the placebo group (15.18 +/- 2.24 min, p < 0.001). Likewise, the saponin extract group had significantly lower bleeding times (11.70 +/- 2.53 min) than the control and placebo groups (p < 0.001 for both comparisons). No differences were found between the notoginseng and the saponin extract groups (p = 0.35). Notoginseng and a saponin extract from notoginseng provide hemostatic effects when applied externally.

Analysis of Variance↗

PubMed2000

Traumatic neuroma after neck dissection: CT characteristics in four cases.

BACKGROUND AND PURPOSE: Traumatic neuroma, an attempt by an injured nerve to regenerate, may present as a palpable nodule or an area sensitive to touch (trigger point) after neck dissection. The purpose of this study was to identify CT characteristics of traumatic neuroma in four patients after neck dissection. METHODS: Between April 1995 and November 1998, the CT studies in three men and one woman (ages, 45-64 years) who had had a radical neck dissection and a nodule posterior to the carotid artery were reviewed retrospectively. CT was performed 1.5 to 6 years after neck dissection with clinical correlation and/or pathologic examination. Three patients had squamous cell carcinoma of the upper aerodigestive tract and one had a primary parotid adenocarcinoma. RESULTS: Three patients with a traumatic neuroma had a centrally radiolucent nodule with peripherally dense rim and intact layer of overlying fat, which was stable on CT studies for 1 to 2 years. One of these had a clinical trigger point. The fourth patient with a pathologically proved traumatic neuroma mixed with tumor had intact overlying fat, but the nodule lacked a radiolucent center and was not close to the carotid artery. CONCLUSION: The CT findings of a stable nodule that is posterior but close to the carotid artery with central radiolucency, a dense rim, and intact overlying fat, combined with the clinical features of a trigger point and a lack of interval growth, strongly suggest the diagnosis of traumatic neuroma.

Carotid Arteries↗

PubMed2000

[Protein secretion from drug-resistant bacteria--a suitable target for new antibiotics].

This paper reviewed the pathways of bacterial protein secretion and discussed the targets of pathogenic bacteria for antibiotics. Inhibition of protein secretion could lead to the growth decline, morphological alteration, and reduction of bacterial virulence, as well as the deprivation of their drug resistant. It was concluded that protein secretion could be a suitable target for new antibiotic agents.

Anti-Bacterial Agents↗

PubMed2000

[An experimental study on F-heparin surface modified IOLs implanted into the Rhesus monkeys' eyes].

OBJECTIVE: To evaluate the biocompatibility of F-heparin surface modified IOLs. METHODS: 13 monkeys were divided into 3 groups, and implanted with different surface modified and non-modified IOLs into their eyes. All of the eyes were examined by slitlamp microscope and Schiötz tonometer at postoperative 15, 30, 60, 90 and 180 days. Postoperatively, at different periods the aqueous was aspirated from the anterior chamber to calculate cells. RESULTS: F-heparin surface modified IOLs induced milder inflammatory reaction and less dense posterior capsula opacification (PCO) than non-modified IOLs. CONCLUSION: F-heparin surface modified IOL has a better biocompatibility.

Animals↗

PubMed2000

[A study on incidence of injury and its socio-economic loss in children and young adults].

OBJECTIVES: To study the current status of incidence of injury among children and young adults and the causes of common injuries, and to estimate its socio-economic loss and extent of harmfulness. METHODS: Pupils in 19 primary and middle schools aged 7 to 18 years, totaling 14,533, were recruited with stratified cluster sampling during 1998 to 1999 in Guangzhou, Maoming, Jiangmen and Shantou. Judgement for injury was based on the following criteria: (1) diagnosed and treated in hospitals or school clinics, (2) a half-day off or more due to injury, and (3) emergency management by pupils' parents or teachers. RESULTS: There were 6 941 pupils suffered from varied injures during the year, with an incidence rate of 47.76% (50.08% for boys and 45.02% for girls). Incidence rate of injury was higher in the middle school pupils (13 - 18 years old, 58.49%) than that in the primary school pupils (7 - 12 years old, 40.08%). The incidence increased significantly with age, with a peak at ages of 13 - 15. Major causes of injuries resulted from falls, injury by sharp articles, collision, traffic injuries and burn/scalds, etc, which usually occurred due to carelessness in sports, playing, walking, bike-riding and working. Frequency of multiple injuries related to the educational level of parents and depended on whether or not an only-child in family. There were 2,173 injured pupils (accounting for 31.3% of the total) visited clinics or emergency department in hospitals and 627 (9.0%) hospitalized for treatment. Twenty-eight percent of the injured pupils were absent from school, with an average absenteeism of 5.6 days. There were 154 injured pupils with transient disability and 53 with permanent disability, with a disability rate of 410.47 per 100,000. Cost for their medical care averaged 81.5 yuan RMB per injured pupil. CONCLUSIONS: Injury was a common and frequently-happened incident among children and young adults and could seriously affect their health, development and growth, studying and their future of children and young adults. Health education, safety-promotion and removing hidden danger for injury are the major measures to prevent from injury, and the government and the whole society should pay great attention to injury issues in children and young adults.

Accidents↗

PubMed2000

[Preclinical pharmacological study of a novel myocardial perfusion agent: 99mTc-Q3].

In order to provide an experimental foundation for clinical study, we made a preclinical pharmacological investigation of 99mTc-Q3, a novel myocardial perfusion imaging agent, technetium-99m-N,N'-ethylenebis (acetylace-toneiminato) bis (tris (3-methoxy-1-proply) phosphine). After the preparation of this compound, the kinetics of blood clearance in rabbits, biodistribution in mice, measurement of plasma protein binding rate, and myocardial perfusion imaging in dog were carried out. The labelling efficiency and radiochemical purity measured were over 99%, and the stability (in vitro) was good and stable up to 6 hr of testing at room temperature. The pharmacokinetics met the two-compartment model with 0.23 +/- 0.09 ml/min of excellent blood clearance, an initial half-time of 1.5979 +/- 0.4182 min, and a late half-time of 203 +/- 25.83 min. The biodistribution as shown in myocardial accumulation was earlier, the radioactive value was higher, and once extracted, it remained relatively constant in the myocardium for at least 4 hr. The tracer was rapidly cleared from the blood, lung and the liver. The scintigraphy imaging in dog demonstrated that it was rapidly cleared from the lung, and the radioactive concentration approached that of background 1 hr after injection. At 15 min after injection, the myocardial imaging displayed clearly up to 3 hr. In vitro protein binding rate was low (7.13 +/- 0.42%). The tolerance of this drug in mice was 500 times as much as in humans. In conclusion, 99mTc-Q3 exhibits favorable stability, biological property and safety, so clinical study of this preparation as a myocardial perfusion imaging agent is worthwhile.

Animals↗