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Biomedical subjects

Y An

Publications and source records attributed to Y An.

At least 19 recordsLinked to original sources
PubMed2002

Determination of toxicokinetic parameters for bioconcentration of water-soluble fraction of petroleum hydrocarbon associated with no. 0 diesel in Changjiang estuary and Jiaozhou bay: model versus mesocosm experiments.

A method is proposed for determination of toxicokinetic parameters for bioconcentration by phytoplankton of the water-soluble fraction (WSF) of petroleum hydrocarbon (PH) associated with No. 0 diesel, in which WSF-PH concentration in phytoplankton cells, C(A(d)), is estimated by subtracting concentration in water (S-bottle) containing a phytoplankton sample from that in a C-bottle without phytoplankton. It was demonstrated that C(A(d)) agrees well with the concentration found by direct ultrasonication extraction of collected cells, C(A(ind)) ( r = 0.88, p < 0.0001), and its uncertainty was about 17.6%. Mesocosms in 25-m3 ethylene vinyl acetate or 4-m3 polyethylene bags were performed at two sites in China: Changjiang Estuary in spring/summer 1998 and Jiaozhou Bay in autumn 1999 and spring/summer 2000. The experiments were designed to determine toxicokinetic parameters, including specific rates of uptake and elimination, and bioconcentration factor (BCF), for bioconcentration of WSF-PH by phytoplankton. A modified kinetic two-compartment model for bioconcentration of WSF-PH by phytoplankton was developed to estimate the toxicokinetic parameters. In the model, the influence of phytoplankton growth on bioconcentration and WSF-PH decline due to biotic and abiotic processes other than bioconcentration, such as volatilization, microbial degradation, phytolysis, and sorption expressed as an exponential-decay equation, are taken into account. Size-dependent BCF was observed in the laboratory experiment. BCFs were 1.0 x 10(4) in summer in Changjiang Estuary, 1.6 x 10(4) in summer, and 1.1 x 10(4) in autumn in Jiaozhou Bay. The difference in BCF may be interpreted by its size dependence.

Biological Availability↗
PubMed2001

Oral exposure of dimethylarsinic acid, a main metabolite of inorganic arsenics, in mice leads to an increase in 8-Oxo-2'-deoxyguanosine level, specifically in the target organs for arsenic carcinogenesis.

We have proposed that oral administration of dimethylarsinic acid (DMA), a metabolite of inorganic arsenics in mammals, rather than inorganic arsenics themselves, promotes lung and skin tumors by way of the metabolic production of free radicals such as dimethylarsenic peroxy radical [(CH(3))(2)AsOO*]. The purpose of the present study was to examine if dimethylarsenic has the ability to induce oxidative damage. 8-oxo-2'-deoxyguanosine (8-oxodG) was used as a biomarker of DNA oxidation. The oral administration of DMA enhanced significantly the amounts of 8-oxodG specifically in the target organs (skin, lung, liver, and urinary bladder) of arsenic carcinogenesis and also in urine, whereas arsenite did not. The dimethylarsenics thus may play an important role in arsenic carcinogenesis through the induction of oxidative damage, particularly of base oxidation.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2001

[Clinical study on the changes of growth hormone/insulin-like growth factor-I axis in patient with obstructive jaundice].

OBJECTIVE: To explore the changes and clinical significance of growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis in patient with obstructive jaundice (OJ). METHODS: The serum GH, GH binding protein (GHBP), IGF-I, endotoxin, prealbumin, and liver function of 60 male in- patients with OJ were investigated 1 day before operation and 1, 3, and 7 days after the operation. Forty male patients with simple gallbladder stone who were hospitalized during the same period as the 60 above mentioned patients, were chosen as controls. RESULTS: The levels of GH, GHBP and IGF-I in patients with obstructive jaundice were significantly lower (7.4 micrograms/L +/- 3.6 micrograms/L, 9.1 +/- 2.3 B/T* 100, and 49.8 mg/L +/- 6.6 mg/L respectively) than those in control group(13.9 micrograms/L +/- 5.7 micrograms/L, 13.3 +/- 1.6 B/T* 100, and 61.4 mg/L +/- 6.5 mg/L respectively, P < 0.01) and were correlated closely with the levels of bilirubin, prealbumin and endotoxin (P < 0.01). CONCLUSION: There is an obvious downregulation of GH-IGF-I axis in patients with OJ probably because of the expression inhibition resulting from dystrophy and endoxemia. It may be one of the important factors mediating the pathophysiological changes in OJ.

Adult↗
PubMed2001

Crystallographic structures of the ligand-binding domains of the androgen receptor and its T877A mutant complexed with the natural agonist dihydrotestosterone.

The structures of the ligand-binding domains (LBD) of the wild-type androgen receptor (AR) and the T877A mutant corresponding to that in LNCaP cells, both bound to dihydrotestosterone, have been refined at 2.0 A resolution. In contrast to the homodimer seen in the retinoid-X receptor and estrogen receptor LBD structures, the AR LBD is monomeric, possibly because of the extended C terminus of AR, which lies in a groove at the dimerization interface. Binding of the natural ligand dihydrotestosterone by the mutant LBD involves interactions with the same residues as in the wild-type receptor, with the exception of the side chain of threonine 877, which is an alanine residue in the mutant. This structural difference in the binding pocket can explain the ability of the mutant AR found in LNCaP cells (T877A) to accommodate progesterone and other ligands that the wild-type receptor cannot.

Amino Acid Sequence↗
PubMed2001

Protein structure prediction using a combination of sequence-based alignment, constrained energy minimization, and structural alignment.

We present a novel approach to protein structure prediction in which fold recognition techniques are combined with ab initio folding methods. Based on the predicted secondary structure, one of two different protocols is followed. For mostly alpha proteins, global optimization and sampling of a statistical energy function is used to generate many low-energy structures; these structures are then screened against a fold library. Any structural matches are then selected for further refinement. For proteins predicted to have significant beta-content, sequence and secondary structure-based alignment is used to identify candidate templates; spatial constraints are then extracted from these templates and used, along with the statistical energy function, in the global sampling and optimization program. Successes and failures of both protocols are discussed.

Algorithms↗
PubMed2001

[Hepatic artery and portal vein dual perfusion chemotherapy in combination with injection of lipiodol-ethanol in treatment of advanced primary hepatocellular carcinoma].

OBJECTIVE: To investigate the therapeutic effects of hepatic artery and portal vein dual perfusion chemotherapy (AVPC) in combination with intratumoral injection of lipiodol-ethanol (IILE) on advanced primary hepatocellular carcinoma (PHC). METHODS: A total of 138 patients with pathologically proven and unresectable PHC were divided into two groups. In group A (n = 80), the patients were treated with PVPC through a hypodermic implanted drug delivery pump. In group B (n = 58), the patients were treated with PVPC + IILE. RESULTS: The total effective rate was 12.6% and 25.9% in group A and group B, respectively. There was a significant difference between the two groups (P < 0.05). The secondary resectable rate was 2.5% and 12.1% in group A and group B, respectively (P < 0.05). The half-, 1- and 2-year survival rates were 56.3%, 45.0% and 21.2% in group A but 81.0%, 61.2% and 39.6% in group B, respectively. There were significant differences bet ween the two groups (P < 0.05). However, there was no marked difference in incidence rate of complications between the two groups (P > 0.05). CONCLUSION: The therapeutic effect of AVPC + IILE on advanced PHC is better than that of PVPC alone.

Adult↗
PubMed2001

[A clinical observation of preserved donor tarsal plate transplantation for repair of tarsus defect].

OBJECTIVE: To investigate the effect of preserved donor tarsal plate transplantation on the repair of the tarsus defect at the time of eye lid tumor removal. METHODS: Donor tarsal plates preserved in pure glycerin were used for the repair of tarsus defects of 58 cases after the complete removal of the eye lid tumors. The grafts were covered with rotated or slid myocutaneous and conjunctival flaps. The associations of the effect with the blood supply, with the size and the preserved time of the donor tarsal plates, as well as with the follow-up time were analyzed by chi(2) test. RESULTS: Of the 43 cases whose plates were fully covered with conjunctival flaps, new blood vessels began growing into the donor tarsal plates one week after the operation. The grafts were vascularized one month later. The donor tarsal plates of 15 cases were only partly covered with conjunctival flaps. As a result, the grafts were vascularized in 2 -- 3 months, and there was dissolution to varying degrees at the surface of the exposed parts of the plates. The effects of the 43 cases with good blood supply were significantly better than the effects of 15 cases with poor blood supply (chi(2) = 5.81, P < 0.05). The sizes of the donor tarsal plates ranged from 5 x 10 mm(2) to 8 x 29 mm(2). Eleven cases were equal or shorter than half of the original sizes of donor tarsal plates, 34 cases were subtotal and 13 cases were total plates. The differences of the sizes led to different results (chi(2) = 6.28, P < 0.05). The preserved times of donor tarsal plates were from 1 week to 2.5 years. However, the results were similar in all cases (chi(2) = 0.99, P > 0.05). All the patients were followed up for 6 months to 10 and half years (mean, 1.8 years). The effects had no statistical significance (chi(2) = 0.85, P > 0.05). The cilia of the donor tarsal plates were preserved in 3 cases, but all of them were totally lost during post-operative one month. After operation slight entropion occurred in 8 cases, slight ectropion in 3 cases, lagophthalmos for 2 -- 3 mm in 7 cases, notch of the palpebral margin in 5 cases and thinness of the donor tarsal plates in 4 cases, but the functional and aesthetic results were normal. Thirty-one cases were cured, 11 cases acquired tangible results and 12 cases were improved. The total effective rate was 93.1%. CONCLUSIONS: The more blood supplies of the donor tarsal plates, the better the effects. So we must make all our efforts to improve the blood supplies of the donor tarsal plates. The effects were associated with the sizes of the plates, but not associated with the preserved times of the grafts and the follow-up times. Preserved donor tarsal plate transplantation for the repair of tarsus defect is a relatively simple operation, the rejection is slight and the result satisfactory, thus it is an ideal plastic material.

Adult↗
PubMed2001

[Development of software of the 24-hour dynamic ECG monitoring and analyzing system].

This paper describes a PC-computer program of a digital remote ECG monitoring system. In addition to current monitor's capabilities of real time displaying of dynamic ECG wave, over-limit alarming, and so on, it has developed most functions of the Holter system, that are recording the data of ECG more than 24 hours, reviewing and analyzing the ECG data, and giving out reports.

Electrocardiography, Ambulatory↗
PubMed2001

[The characteristic infrared spectra of N-(2-phenyl-(1,2,3-triazole-formyl)-N'-arylthioueas].

The characteristic infrared spectra of N-(2-phenyl-(1,2,3-triazole-formyl)-N'-aryl)-thioueas have been studied and the changing rules with the change of chemical structure have been discussed. Specially, the effect of the characteristic infrared of long-range radical by different substitute is discussed in detail. Results show that characteristic bands of radical which as far as five radicals away form substitute group are still affected. It is very suggestive meaning for long-range spectra research.

Anti-Infective Agents↗
PubMed2000

Liquid chromatographic assay for a glucose tetrasaccharide, a putative biomarker for the diagnosis of Pompe disease.

A HPLC method associated with butyl-p-aminobenzoate derivatization has been developed for the analysis of a tetraglucose oligomer, Glcalpha1-6Glcalpha1-4Glcalpha1-4Glc, designated Glc(4), in biological fluids. This tetraglucose, normally excreted in the urine, has previously been shown to be elevated in a number of pathological conditions including Pompe disease (glycogen storage disease type II), which is caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase. Concentrations of Glc(4) in both urine and plasma were established for the age ranges of <1, 1-5, 6-10, 11-20, and >20 years, both in normal individuals and in a cohort of 21 patients with enzymatically confirmed Pompe disease. The Glc(4) concentration decreased with age in both groups, but all the patients had elevated Glc(4) levels compared with age-matched controls. Electrospray tandem mass spectrometry was employed to establish the homogeneity of the HPLC peak for Glc(4) and to investigate the identity of other unusual oligosaccharides excreted in patient urine. Our results demonstrate that this method is suitable for application in clinical laboratories to help establish the diagnosis of Pompe disease.

Adolescent↗
PubMed2000

Intraarterial protein delivery via intimally-adherent bilayer hydrogels.

Arterial structure plays an important role in drug delivery from intraarterial depots. The internal elastic lamina forms a major diffusive resistance to the transport of macromolecular drugs from intimally-adherent hydrogel depots to the arterial media. The objectives of this study were to develop an approach by which to form a bilayer hydrogel depot with a higher permeability intimally-adherent layer, containing the drug, and a lower permeability luminal layer, and to evaluate ex vivo whether this luminal layer could enhance the delivery of a protein to the arterial media. Sequential interfacial photopolymerization of polyethyleneglycol diacrylate precursors (molecular weight 4000 for the luminal layer, 10,000 for the intimal layer) with eosin Y and triethanolamine as an initiation system was employed to form these bilayer hydrogels. Horseradish peroxidase was used as a model protein, and delivery to the arterial media was measured in rat carotid arteries ex vivo. The lower permeability luminal layer served to enhance delivery of the model protein into the arterial media for delivery periods at least up to 72 h. Thus, it was possible to compensate for the diffusional resistance of the internal elastic lamina on the one side of the hydrogel depot with a second diffusional resistance on the other side of the hydrogel.

Animals↗
PubMed2000

Cysteine-independent polymerization of metallothioneins in solutions and in crystals.

Polymerization of metallothioneins is one of the usually encountered puzzles during the research process of metallothioneins' structure and function. Our work focuses on the cysteine independently occurred polymerization from metallothioneins monomers in different milieus, while it leaves out the aggregation caused by the oxidation of cysteine, because the latter circumstance is the result of purification lapsus. After the purification of metallothioneins monomers, a dynamic light-scattering technique is used to detect the polymerized states of rabbit liver metallothionein I and II in different buffers, which is the first systematical detection of polymerized states of metallothioneins in solutions. The effects of different compositions of each buffer are discussed in details. Steric complementarity, hydrophobic, and electrostatic interaction characteristics are studied, following the modeling of monomers and relevant polymers of rat metallothionein II, rabbit liver metallothionein I and II. These theoretical calculations are the first complete computer simulations on different factors affecting metallothioneins' polymerization. A molecular recognition mechanism of metallothioneins' polymerization in solutions is proposed on the bases of experimental results and theoretical calculations. Preliminary X-ray studies of two crystal forms of rabbit liver metallothionein II are compared with the crystal structure of rat metallothionein II, and the polymerized states in crystal packing are discussed with the knowledge of polymerization of metallothioneins in solutions. The hypothesis, which is consistent with theoretical calculations and experimental results, is expected to construct a connection between the biochemical characteristics and physiological functions of metallothioneins, and this research may give some enlightenment to the topics of protein polymerizations.

Amino Acid Sequence↗
PubMed2000

Effects of lanthanum and calcium on photoelectron transport activity and the related protein complexes in chloroplast of cucumber leaves.

The effects of lanthanum and calcium ions on electron transport, dichlorephenol indophenol (DCIP) photoreduction, and oxygen evolution activities in chloroplast from cucumber (Cucumis satives L.) were determined. The lanthanum inhibited the whole electron chain-transport activity of chloroplast. DCIP photoreduction and oxygen evolution activities of the photosystem I (PSII) also decrease after treatment with La3+. But the diminished activities of PSII and chloroplast caused by La3+ could be reversed by Ca2+ and even became higher than the control level. The concentration analysis of related protein complexes to photoelectron transport in chloroplast included that La3+ induced the concentration of chlorophyll protein complexes increasing but caused some nonchlorophyll protein complexes to decompose partially. This increasing effect of La3+ on chlorophyll protein complexes results in the improvement of chlorophyll content, which will improve the absorption of photoelectron and energy transport in the process of photosynthesis.

2,6-Dichloroindophenol↗
PubMed2000

[MRI features of confusable tumors of orbital apex].

OBJECTIVE: To analyze magnetic resonance imaging (MRI) features of confusable tumors including cavernous hemangioma, cavernous lymphangioma and neurilemmoma located at orbital apex, which could provide evidences for diagnosis and surgical treatment. METHODS: MRI was performed on 16 cases with tumors of orbital apex confirmed by pathology, and their MRI findings were analyzed. RESULTS: The time taken to attain complete enhancement after contrast on MRI was significantly different in the three types of tumor (P < 0.01) Their enhancement patterns were related to their pathologic findings. CONCLUSIONS: The different enhancement patterns of various tumors of orbital apex are characteristic for diagnosis and differential diagnosis.

Adolescent↗
PubMed2000

[Expression of substance P receptor mRNA in nasal mucosa of rat in allergic rhinitis model].

OBJECTIVE: To study the expression of substance P receptor messenger RNA (SP-R mRNA) in nasal mucosa in allergic rhinitis (AR) rat model. METHODS: Twenty Wistar rats free of disease were randomly divided into two groups. AR model rats were established through repeated intraperitoneal shot of ovalbumin (OV) and consequently confirmed by local challenge with OV. SP-R mRNA in nasal mucosa, obtained from two groups, were used to do reverse transcriptive polymerase chain reaction (RT-PCR) and Southern blot. beta-actin was used as a standard control through out the whole process. RESULTS: The results showed definitely that there were positive expression of SP-R mRNA in normal nasal mucosa. This expressions increased significantly (P < 0.05) during nasal allergy. CONCLUSION: Increased expression SP-R mRNA in nasal mucosa in AR model might play roles in the development of AR.

Animals↗
PubMed2000

Protective effect of melatonin on neural cells against the cytotoxicity of oxyradicals.

OBJECTIVE: To investigate the exact mechanism of melatonin to prohibit the apoptosis of neural cells induced by various kinds of cytotoxic agents. METHODS: We used the methods of phase contrast microscopy, MTT assay and hoechst dye staining to check this mechanism in SKNSH and U251 cell lines. RESULTS: Both 2 mmol/L H2O2 and 0.5 micromol/L amyloid beta-protein (Abeta) induce these two cell lines die via apoptosis. Either melatonin or glutathione can significantly protect both cell lines. The protective effect of 10 micromol/L melatonin is as same as that of 60 micromol/L glutathione. CONCLUSION: Melatonin can partly inhibit the cytotoxicity of H2O2 and Abeta through its role as a free radical scavenger.

Amyloid beta-Peptides↗
PubMed2000

[Construction of BPI23-Fc gamma 1 recombinant protein prokaryotic expression vector and the expression and biological assessment of BPI23-Fc gamma 1 recombinant protein].

OBJECTIVE: To construct pBV-BPI600-Fc gamma 1(700) recombinant expression vector, to transform into Escherichia coli DH5 alpha, and to induce the expression of BPI23-Fc gamma 1 anti-bacterial recombinant protein. METHODS: Genes which encode BPI23 and Fc gamma 1 were amplified by RT-PCR from mRNA that was extracted from HL-60 cell and normal human leukocytes; Recombinant cloning vector and recombinant expression vector were constructed. pBV-BPI600-Fc gamma 1(700) recombinant expression vector was transformed into the competent Escherichia coli DH5 alpha and BPI23-Fc gamma 1 recombinant protein was expressed by temperature induced method. RESULTS: (1) Expected amplified products BPI600 bp and Fc gamma 1(700) bp were obtained by RT-PCR. (2) pUC18-BPI180, pUC18-BPI420, and pUC18-Fc gamma 1(700) recombinant cloning vector were successfully constructed, and sequences were identical with the reported ones. (3) pBV-BPI600-Fc gamma 1(700) recombinant expression vector was successfully constructed, and results of the enzyme digestion analysis were identical with expected ones. (4) pBV-BPI600-Fc gamma 1(700) recombinant expression vector was transformed into the competent Escherichia coli DH5 alpha and BPI23-Fc gamma 1 recombinant protein was expressed by temperature-induced method, and its expression level was accounted for 20% of total bacterial proteins. (5) The renatured BPI23-Fc gamma 1 recombinant protein had anti-bacterial activity and biological functions of complement fixation, opsonization. CONCLUSION: pBV-BPI600-Fc gamma 1(700) recombinant expression vector was successfully constructed, and BPI23-Fc gamma 1 recombinant protein with BPI and IgGFc double biological activity was expressed in Escherichia coli.

Antimicrobial Cationic Peptides↗