Biomedical subjects

Y Fang

Publications and source records attributed to Y Fang.

At least 91 records · Page 5Linked to original sources

PubMed2000

Ferrocenecarboxaldehyde labeled DNA probe for the study on DNA damage and protection.

A ferrocenecarboxaldehyde (FCA) labeled DNA probe is used for the first time in the study of DNA damage and protection. The electrochemically active reagent FCA was labeled successfully on to a denatured calf-thymus DNA by 1-ethyl-3- (3-dimethyl-aminopropyl) carbodiimide (EDC). The FCA labeled DNA probe was used to hybridize with the sample DNA sequence accumulated on the surface of a graphite electrode. The anodic peaks of the FCA bound to the double-stranded DNA (dsDNA) by differential pulse voltammetry (DPV) were used for the detection of DNA damage and protection. Thiourea, sodium benzoic acid and isopropanol can decrease DNA damage by hydroxyl radicals, and their protection efficiencies are discussed.

Animals↗

PubMed2000

Photokinetic voltammetric method for the determination of thiocyanate.

Thiocyanate traces have a strong inhibitory effect on the oxidation of Neutral Red by potassium bromate under UV irradiation in diluted phosphoric acid. Neutral Red exhibits a sensitive second derivative oscillopolarographic wave at -0.6 V(vs. SCE) in diluted phosphoric acid and sodium acetate solution. The oscillopolarographic behavior of Neutral Red was selected as indicator component for its photo-activated oxidation. The photochemical reaction rate equation was determined. A detection limit of 0.3 ng mL(-1) (3sigma/k) and a linear calibration curve from 2.0-48.0 ng mL(-1) thiocyanate were obtained. The method was applied to the determination of thiocyanate in urine, saliva and serum with satisfactory results.

Journal Article↗

PubMed2000

Determination of idarubicin in human urine by capillary zone electrophoresis with amperometric detection.

A simple, reliable and reproducible method, based on capillary zone electrophoresis with amperometric detection, has been developed for the determination of idarubicin in human urine. A carbon disk electrode was used as working electrode. The optimal conditions of separation and detection were pH 5.6 phosphate buffer (0.20 mol/L), 22 kV for the separation voltage and 1.00 V (vs. Ag/AgCl, 3 mol/L KCl) for the detection potential. The linear range was from 4.0 x 10(-7) to 2.0 x 10(-5) mol/L with a regression coefficient of 0.9986, and the detection limit was 8.0 x 10(-8) mol/L. The method was directly applied to the determination of idarubicin in spiked human urine without any other sample pretreatment except filtration, and the assay results were satisfactory.

Antibiotics, Antineoplastic↗

PubMed2000

Catalytic determination of ultra trace amounts of tellurium by 2.5-order differential oscillopolarography.

A highly sensitive and selective catalytic method with 2.5-order differential oscillopolarographic detection is described for the determination of tellurium, based on its activation effect on the slow Pd(II)-catalyzed reaction of sodium hypophosphite and methyl red in hydrochloric acid medium at 100 degrees C. Methyl red exhibited a sensitive 2.5-order differential polarographic wave at -0.35 V (vs. SCE) in the supporting electrolyte of pH 5.0 acetate buffer solution and was chosen as the indicating component for the indirect determination of tellurium. A calibration curve of tellurium in the range of 0.02-2.0 ng mL(-1) was obtained by the fixed-time procedure. The detection limit was 0.007 ng mL(-1). Possible interferences by co-existing substances were examined. The new method has been used to analyze trace tellurium in organs of white mice with satisfactory results. RSD was 0.54% to 2.10%, recovery 98.4% to 95.7%. The mechanism is also discussed.

Azo Compounds↗

PubMed2000

Recurrent chromosome changes in 62 primary gastric carcinomas detected by comparative genomic hybridization.

Comparative genomic hybridization (CGH) has been applied to detect recurrent chromosome alterations in 62 primary gastric carcinomas. Several nonrandom chromosomal changes, including gains of 8q (31 cases, 50%), 20q (29 cases, 47%) with a minimum gain region at 20q11. 2-q12, 13q (21 cases, 34%) with a minimum gain region at 13q22, and 3q (19 cases, 31%) were commonly observed. The regions most frequently lost included: 19p (23 cases, 37%), 17p (21 cases, 33%), and 1p (14 cases, 23%). High copy number gain (DNA sequence amplification) was detected in 6 cases. Amplification of 8q23-q24.2 and 20q11.2-q12 were observed in 3 cases. Gain of 20q and loss of 19p were confirmed by fluorescence in situ hybridization using corresponding bacterial artificial chromosomes (BAC) clones from those regions. The gain and loss of chromosomal regions identified in this study provide candidate regions involved in gastric tumorigenesis.

Adult↗

PubMed2000

Endogenous GM1 ganglioside of the plasma membrane promotes neuritogenesis by two mechanisms.

The influence of GM1 on the neuritogenic phase of neuronal differentiation has been highlighted in recent reports showing upregulation of this ganglioside in the plasma and nuclear membranes concomitant with axonogenesis. These changes are accompanied by alterations in Ca2+ flux which constitute an essential component of the signaling mechanism for axon outgrowth. This study examines 2 distinct mechanisms of induced neurite outgrowth involving plasma membrane GM1, as expressed in 3 neuroblastoma cell lines. Growth of Neuro-2a and NG108-15 cells in the presence of neuraminidase (N'ase), an enzyme that increases the cell surface content of GM1, caused prolific outgrowth of neurites which, in the case of Neuro-2a, could be blocked by the B subunit of cholera toxin (Ctx B) which binds specifically to GM1; however, the latter agent applied to NG108-15 cells proved neuritogenic and potentiated the effect of N'ase. With N18 cells, the combination was also neuritogenic as was Ctx B alone, whereas N'ase by itself had no effect. Neurite outgrowth correlated with influx of extracellular Ca2+, determined with fura-2. Treatment of NG108-15 and N18 cells with Ctx B alone caused modest but persistent elevation of intracellular Ca2+ while a more pronounced increase occurred with the combination Ctx B + N'ase. Treatment with N'ase alone also caused modest but prolonged elevation of intracellular Ca2+ in NG108-15 and Neuro-2a but not N18; in the case of Neuro-2a this effect was blocked by Ctx B. Neuro-2a and N18 thus possess 2 distinctly different mechanisms for neuritogenesis based on Ca2+ modulation by plasma membrane GM1, while NG108-15 cells show both capabilities. The neurites stimulated by N'ase + Ctx B treatment of N18 cells were shown to have axonal character, as previously demonstrated for NG108-15 cells stimulated in this manner and for Neuro-2a cells stimulated by N'ase alone.

Cell Membrane↗

PubMed2000

[A study on the trend of tuberculosis in an area of Shanghai City using mathematical model].

A widely-used mathematical model (compartmental model) in epidemiological studies was utilized to analyze the tuberculosis situation in area Y of Shanghai from 1971 till 1994. In this model, the whole population was divided into 5 groups, (susceptible, latent, prevalent, healed and immune). Six parameters (effective BCG coverage, immune loss rate, infection rate, disease risk, cure rate and heal loss rate) were introduced and discussed to describe the transmission of tuberculosis. The computed tuberculosis data from this model agree quite well with the observed data. The results show that the susceptible group is the largest among all groups. In 1994, the annual risk of infection was estimated to be 0.26%. It is predicted that elderly people will comprise an increasing percentage of tuberculosis patients in the future. It is also found that it will still take a long time to eliminate tuberculosis under current medical situations.

China↗

PubMed2000

[Short-term memory performance of German and Chinese probands with verbal and figural items: on the function of the phonological loop and visual-spatial sketchpad].

In a computer-controlled experiment using n = 48 German and n = 48 Chinese subjects we established the memory span for simple geometrical figures and their names in the subjects' respective native language. Half of the subjects replied verbally, the other half nonverbally via a touch screen. In addition, verbal reproduction times were measured. Significant differences in memory span between the two language groups were found only under nonverbal report conditions: here, the Chinese subjects achieved better results than their German contemporaries. There were no differences in oral reproduction times between the two groups. The results are discussed within the framework of Baddeley's working memory model.

Adolescent↗

PubMed2000

Recurrent chromosome alterations in hepatocellular carcinoma detected by comparative genomic hybridization.

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and has a very poor prognosis. Fifty primary HCC cases have been analyzed in the present study to explore the association between genomic alteration in primary HCC and clinical features. Several recurrent chromosomal abnormalities were identified in this study. The most frequently detected chromosomal gains involved chromosome arms 1q (33/50 cases, 66%), 8q (24/50 cases, 48%), and 20q (10/50 cases, 20%). High-copy-number amplifications involving 1q (4 cases), 8q (3 cases), and 20q (3 cases) were detected, and a minimum overlapping amplified region at 1q12-q22 was identified. The most frequently detected loss of chromosomal material involved 16q (35/50 cases, 70%), 17p (26/50 cases, 52%), 19p (21/50 cases, 42%), 4q (20/50 cases, 40%), 1p (18/50 cases, 36%), 8p (16/50 cases, 32%), and 22q (14/50 cases, 28%). The associations between genomic alterations detected in the present study and clinical features including clinical stage, tumor size, HBV infection, chronic liver disease, and liver cirrhosis were explored. Our CGH results suggest that the gain of 20q and deletion of 8p are late genetic alterations in HCC, because the incidence of these alterations was obviously increased in the advanced clinical stages. Another finding showed that loss of 8p and gain of 8q and 20q are associated with tumor size. The recurrent gain and loss of chromosomal regions identified in this study provide candidate regions that may contain oncogenes or tumor suppressor genes respectively involved in HCC development and progression.

Adult↗

PubMed2000

[The experimental study on material basis of motor skill plasticity after acute cerebral infarction].

OBJECTIVE: To investigate the structure basis of motor skill plasticity and the recovery mechanism after acute cerebral infarction. METHODS: After MCAO, the motor skill of rats was examined via beam walking test; and the neuron, synapse and the distribution of neurofilament (NF), microtubule associated protein 2 (MAP2), growth associated protein 43 (GAP43) and synaptophysin (SYP) were observed by electron scope and immunohistology staining. RESULTS: All rats had paralysis after MCAO. The motor skill began to recover significantly at the end of 3 weeks, and kept to improve. The number of injured neuron decreased to normal level at week 9 after an increase resulted from MCAO(1st week: 74.6 +/- 8.8/200 field, 9th week: 2.6 +/- 2.5/200 field); the number and structure of synapse regained to normal level gradually, at last outstripped the control group (number of synapse, 1st week: 8.8 +/- 1.7/8,000 field, 9th week: 15.3 +/- 2.4/8,000 field; normal control: 12.3 +/- 2.0/8,000 field); So did SYP, NF and MAP2. The GAP43 increased only at week 1. CONCLUSION: With the reduction of apoptosis cell, the relevant changes in the number, function and structure of synapse form the material basis of motor skill's plasticity together after cerebral infarction. The regeneration of neuron dose not play important role in motor skill recovery.

Acute Disease↗

PubMed2000

[Changes after dynamic observation of ultrastructural cerebral infarction in renovascular hypertensive rats].

OBJECTIVE: To study the ultrastructural damages of brain tissues dynamically after middle cerebral artery obstruction (MCAO). METHODS: A middle cerebral artery obstruction (MCAO) model was reproduced in renal vascular hypertensive rats (RHR). Brain tissues in different locations were collected for eight times in row, from two hours to seven days after establishment of the animal model. RESULTS: The changes occurred in the whole brain after focal cerebral ischemia. The severity of impairment and time of emergence differed with the location sampled. The earliest in the infarcted region with necrosis was considered the major change and completely irreversible damage. The next was seen in marginal regions, mainly with microvascular collapse, formation of microthrombi, and partial necrosis of brain cells and was considered partially reversible damage. The last was in distant and contralateral hemisphere, mainly with reversible swelling of endothelial cells and astrocytes. Changes in the MCAO models reproduced by RHR models were much similar to the clinical pathological changes in cerebral infarction based on the hypertensive cerebrovascular impairment, and it was regarded as a relatively ideal model for studying focal ischemic cerebral impairment. CONCLUSION: Dynamic changes of cerebral ultrastructure in which microvascular impairment plays an important role suggest that clinical therapy cannot only be focused on infarction foci, but also on the whole brain with comprehensively effective measurements.

Animals↗

PubMed2000

Preclinical trials of human erythrocyte superoxide dismutase injection.

OBJECTIVE: To assess the quality of human erythrocyte superoxide dismutase (SOD) injection reaching the official standard for its clinical uses. METHODS: Human erythrocyte SOD injection prepared by McCord-Fridovich's method without column chromatography but with some modifications was used in preclinical trials, to observe the general pharmacology and pharmacodynamics of the product. RESULTS: The quality of human erythrocyte SOD injection conformed to the official standard of a biological product, which was found to be non-toxic and did not have any effects on the central and autonomic nervous systems as well as cardiovascular and respiratory systems. The efficacy of anti-inflammation and promotion of immuno-regulation especially on carrageenan and adjuvant-induced polyarthritis were shown in animals. CONCLUSION: Human erythrocyte SOD injection is appropriate for prophylactic and therapeutic uses in clinical trials.

Animals↗

PubMed2000

A preliminary investigation of Tanakan in the treatment of hypertensive arteriosclerosis and stroke in rats.

OBJECTIVE: To observe the changes in hypertensive cerebral arteriosclerosis and the incidence of stroke in rats following treatment with Tanakan, a preparation of Ginkgo Biloba (GB). METHODS: Using two-kidney, two clip renovascular hypertensive rats (RHRs) as animal models--we investigated changes in these hypertensive arteriosclerosis-associated factors: A I, A II, ALD, ET, SOD and cGMP. Blood levels were observed after oral administration of GB, at both early and late stages of hypertension. RESULTS: The degree of arteriosclerosis was more severe in both RHRs control and the later treated group than in the early treated group, with blood levels of A I, A II, ALD and ET in the former two groups significantly elevated. The degree of arteriosclerosis in the early treated group decreased and the blood levels of A I, A II, ALD and ET in this group decreased nearly to normal levels. The blood levels of SOD and cGMP were also elevated in the early treated group. CONCLUSIONS: These results reveal that it is important to treat hypertension as soon as possible, in order to reduce the occurrence of stroke.

Animals↗

PubMed2000

[Response to milrinone treatment in patients with chronic congestive heart failure].

The objective of this study was to examine the efficacy of milrinone in chronic congestive heart failure. In this randomized, double-blind, placebo-controlled trial, 30 patients with class III or IV chronic congestive heart failure were randomly assigned to receive milrinone (n = 15) or placebo (n = 15). The results showed that in the milrinone group, stroke volume increased from 38.50 +/- 5.34 to 64.93 +/- 6.46 ml (P < 0.001), cardiac output increased from 3.39 +/- 0.42 to 5.28 +/- 0.55 L/min (P < 0.001), cardiac index increased from 2.01 +/- 0.42 to 3.21 +/- 0.57/min/m2 (P < 0.001) and ejection fraction increased from 0.23 +/- 0.05 to 0.35 +/- 0.06(P < 0.001). In the placebo group, no hemodynamic effects were found. Milrinone favourably influenced the symptoms and heart function in 11/15(73.3%) patients. In the placebo group, only 4/15(26.7%) patients had such response (P < 0.05). These data indicate that milrinone is effective for improving the hemodynamics status and heart function in patients with chronic heart failure.

Adolescent↗

PubMed2000

[The determination of cantharidin in AIDI liquid injection by gas chromatography].

A method for the determination of cantharidin in AIDI liquid injection with gas chromatography is described. The cantharidin was extracted with dichloromethane and then determined by gas chromatography with OV-17 packed column and FID detector. Its distribution constant between dichloromethane and water was 480. The extraction recoveries of cantharidin were 99%-102%. The calibration curve was Y = -113 + 35,900X, r = 0.9999 and the detection limit was 0.02 mg/L in liquid injection. As the results showed, the method is simple, rapid, sensitive and precise for determining cantharidin in AIDI liquid injection.

Antineoplastic Agents↗

PubMed1999

A multiple-capillary electrophoresis system for small-scale DNA sequencing and analysis.

A five-capillary system has been developed for DNA sequencing and analysis. The post-column fluorescence detector is based on a sheath-flow cuvette. The instrument provides uniform and continuous illumination of the samples. The cuvette virtually eliminates cross-talk in the fluorescence signal between capillaries. Discrete single-photon counting avalanche photodiodes provide high efficiency light detection. The instrument has detection limits (3sigma) of 130 +/- 30 fluorescein molecules injected onto each capillary. Over 650 bases of sequence at 98.8% accuracy were generated in 100 min at 50 degrees C from M13mp18. Separation and detection of short tandem repeats proved efficient and accurate with the use of internal standards for direct comparison of migration times between capillaries.

Adult↗

PubMed1999

Mode-specific inhibition of sodium-calcium exchange during protein phosphatase blockade.

The effects of the protein phosphatase inhibitors calyculin A and okadaic acid on Na(+)/Ca(2+) exchange activity were examined in transfected Chinese hamster ovary cells expressing the bovine cardiac Na(+)/Ca(2+) exchanger. Incubating the cells for 5-10 min with 100 nM calyculin A reduced exchange-mediated (45)Ca(2+) uptake or Ba(2+) influx by 50-75%. Half-maximal inhibition of (45)Ca(2+) uptake was observed at 15 nM calyculin A. The nonselective protein kinase inhibitors K252a and staurosporine provided partial protection against the effects of calyculin A. Okadaic acid, another protein phosphatase inhibitor, nearly completely blocked exchange-mediated Ba(2+) influx. Chinese hamster ovary cells expressing a mutant exchanger in which 420 out of 520 amino acid residues were deleted from the central hydrophilic domain of the exchanger remained sensitive to the inhibitory effects of calyculin A and okadaic acid. Surprisingly, Na(o)(+)-dependent Ca(2+) efflux appeared to be only modestly inhibited, if at all, by calyculin A or okadaic acid. We conclude that protein hyperphosphorylation during protein phosphatase blockade selectively inhibits the Ca(2+) influx mode of Na(+)/Ca(2+) exchange, probably by an indirect mechanism that does not involve phosphorylation of the exchanger itself.

Animals↗

PubMed1999

Cocaine upregulates the dopamine transporter in fetal rhesus monkey brain.

Cocaine is a highly addictive drug that binds to the dopamine transporter (DAT), inhibits the reuptake of dopamine, and initiates multiple actions within midbrain dopaminergic systems. Using the rhesus monkey, we have investigated the consequences of in utero cocaine exposure on the expression of DAT in the fetal brain. By using the selective DAT ligand [125I]RTI-121 and tyrosine hydroxylase (TH) immunocytochemistry, we found that DAT binding sites are highly developed by day 70 of gestation and show a distribution pattern similar to TH. The rank order of specific 3beta-(4-[125I]iodophenyl)tropane-2beta-carboxylic acid isopropyl ester ([125I]RTI-121) binding densities was substantia nigra-ventral tegmental area > putamen > caudate > lateral hypothalamus > accumbens > linear/interfascicular nuclei >/= globus pallidus > prefrontal cortex. Furthermore, we observed that DAT mRNA was differentially expressed within fetal midbrain dopamine neurons with the highest levels detected in the ventral tier of the substantia nigra pars compacta, and the lowest levels in the ventral tegmental area and the linear/interfascicular nuclei. In utero cocaine exposure between days 22 and 70 significantly increased DAT mRNA expression, and the density of [125I]RTI-121 binding sites within midbrain dopamine neurons in the 70-d-old fetus. This increased DAT expression is accompanied by other presynaptic and postsynaptic neuronal changes, which collectively suggest that midbrain dopamine neurons are hypoactive after prolonged cocaine exposure, a state that may be a contributing factor in the development of attention deficit disorders observed in subjects exposed prenatally to cocaine.

Animals↗