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Biomedical subjects

Y Yuan

Publications and source records attributed to Y Yuan.

At least 163 records · Page 9Linked to original sources
PubMed1998

The effect of oxygenated mycolic acid composition on cell wall function and macrophage growth in Mycobacterium tuberculosis.

There are three major structural classes of mycolic acids in the cell envelope of Mycobacterium tuberculosis (MTB): alpha-, methoxy- and ketomycolate. The two oxygen-containing classes are biosynthetically related through a common alpha-methyl hydroxymycolate intermediate. BCG strains that fail to produce methoxymycolate and instead produce only keto- and alpha-mycolic acids show apparent defects in the O-methyltransferase MMAS-3. Overproduction of MMAS-3 from MTB resulted in a complete replacement of ketomycolate by methoxymycolate in both BCG and MTB. In vitro growth of these recombinant strains lacking ketomycolate was impaired at reduced temperatures but appeared to be normal at 37 degrees C. Glucose uptake was significantly decreased in such strains, but uptake of chenodeoxycholate and glycine was unaffected. Although sensitivity to INH remained unchanged, these cells were found to be hypersensitive to ampicillin and rifampicin. Infectivity of BCG and H37Rv wild type or MMAS-3 overproducers in THP-1 cells was somewhat affected, but the ability of the strains lacking ketomycolate to grow within this macrophage-like cell line was severely compromised. In vivo labelling of mycolic acids during growth of H37Rv within THP-1 cells revealed a substantial increase in ketomycolate and alphamycolate synthesized by intracellularly grown mycobacteria. These results establish a critical role for mycolate composition in proper cell wall function during the growth of MTB in vivo.

Amino Acid Sequence↗
PubMed1998

Relative biologic availability and pharmacokinetics of albuterol preparations in healthy Chinese.

The authors' goal was to study the biologic availability and pharmacokinetics of two different formulations of controlled-release (CR) tablets of albuterol. A two-way, cross-over biologic availability study was performed with 20 healthy male volunteers to evaluate the relative biologic availability of two CR tablets of albuterol versus two different formulations of immediate-release (IR) albuterol tablets. Albuterol concentrations in plasma were measured using an HPLC procedure. Each patient subject received a 4.8-mg CR tablet every 12 hours for 6 days and a 4.8-mg IR tablet every 8 hours for 6 days. Tests of single doses and steady state were assayed for CR and IR albuterol tablets. The mean Cmax and tmax for two CR tablets given after a single dose were 7.3+/-1.5, 7.9+/-1.4 microg x L(-1) and 4.6+/-0.8, 4.8+/-0.5 hours, respectively. The Cmax and tmax for two IR tablets given after a single dose were 12.5-/+1.3, 15.3 +/-2.3 microg x L(-1) and 1.3+/-0.4, 1.6+/-0.4 hours, respectively. The relative biologic availability of two CR albuterol tablets were 106.0+/-6.2% and 109.8+/-9.0%, respectively. Administration of CR albuterol twice a day provides an alternative to administration of IR albuterol three or four times a day.

Adult↗
PubMed1998

Tyrosine phosphorylation of paxillin/pp125FAK and microvascular endothelial barrier function.

The transendothelial movement of solutes is a dynamic process controlled by a complex interaction between the cytoskeleton and adhesion proteins. The aim of this study was to examine whether protein tyrosine phosphorylation is involved in the regulation of endothelial barrier function. The apparent permeability coefficient of albumin (Pa) was measured in isolated and perfused coronary venules. Tyrosine phosphatase inhibitors, including phenylarsine oxide and sodium orthovanadate, dose and time dependently increased basal Pa. Western blot analysis of cultured coronary venular endothelial cells revealed that inhibition of tyrosine phosphatase induced an increase in phosphotyrosine content in a number of proteins, including bands at 65-70 and 120-130 kDa, which were identified as paxillin and focal adhesion kinase (pp125FAK), respectively. The time course and dose responsiveness of protein tyrosine phosphorylation were tightly correlated with those of increases in Pa. Furthermore, stimulation of endothelial cells with histamine or phorbol myristate acetate (PMA) enhanced tyrosine phosphorylation of paxillin and pp125FAK, which was blocked by the tyrosine kinase inhibitor damnacanthal. Correspondingly, the increases in venular permeability elicited by histamine and PMA were abolished in damnacanthal-treated venules. Taken together, the data suggest a possible involvement of protein tyrosine phosphorylation in the control of endothelial barrier function. Paxillin and its associated focal adhesion proteins may play a specific role in agonist-induced hyperpermeability responses in the endothelium of exchange vessels.

Animals↗
PubMed1998

Neutrophil-dependent augmentation of PAF-induced vasoconstriction and albumin flux in coronary arterioles.

Platelet-activating factor (PAF) has been implicated in the pathogenesis of ischemic heart disease, reperfusion injury, and inflammatory reactions. Although neutrophils have been shown to primarily mediate PAF-induced microvascular dysfunction, the vasoactive effect of PAF and its neutrophil-dependent mechanism have not been directly and systematically studied in coronary resistance vessels. Therefore, the aim of this study was to examine the effects of PAF on coronary arteriolar function and neutrophil dynamics using an isolated and perfused microvessel preparation. Topical application of PAF to the vessels induced a dose-dependent decrease in the diameter but an increase in the apparent permeability coefficient of albumin. Disruption of the endothelium abolished the vasomotor response to PAF, and perfusion of neutrophils significantly augmented PAF-induced changes in vasomotor tone and permeability. Furthermore, the interaction between neutrophils and the endothelium was studied in the intact perfused coronary arterioles. Under control conditions, there were no adherent neutrophils observed in the vessels at varied intraluminal flow velocities. However, administration of PAF caused neutrophil adhesion to the endothelium of coronary arterioles at low flow velocities. Western blot analysis indicated that PAF upregulated the expression of intercellular adhesion molecule-1 in cultured coronary microvascular endothelial cells. Taken together, the results suggest that 1) PAF induces vasoconstriction and hyperpermeability in coronary arterioles via an endothelium-dependent and neutrophil-mediated mechanism, and 2) PAF is able to stimulate neutrophil adhesion in coronary arterioles under a condition of low flow rate.

Animals↗
PubMed1998

Efficient protein transfection of cultured coronary venular endothelial cells.

Although it is well recognized that microvascular endothelial cells play an important role in the local regulation of tissue perfusion and exchange processes, the precise effect of specific endothelial proteins on microvascular function remains to be elucidated. The lack of information is partially due to methodological limitations, because pharmacological approaches that are routinely used in conventional microcirculatory studies produce nonspecific information. The purpose of this study was to develop an efficient method of transfecting endothelial cells with proteins for functional analysis. TransIT, a polyamine reagent, proved very successful for beta-galactosidase (beta-Gal) protein transfection of bovine coronary venular endothelial cells, because time-course and dose-dependent experiments showed that a transfection efficiency of 88 +/- 7% was possible. In control studies, beta-Gal was detected in transfected cells that were trypsinized and washed, indicating that the protein was not merely adhering to the cell surface. Furthermore, transfection of a cell-impermeable peptide inhibitor of protein kinase C (PKC) resulted in a decrease in PKC activity in comparison with control cells. This approach provides a technical basis for further transfection of endothelial cell monolayers with antibodies and constitutively active or dominant-negative proteins to study the molecular control of microvascular function.

Animals↗
PubMed1998

Presence of antibodies to heat stress proteins in workers exposed to benzene and in patients with benzene poisoning.

Heat shock or stress proteins (Hsps) are a group of proteins induced by a large number of xenobiotics, many of which are common in the working and living environment. The biological significance of the presence of antibodies against Hsps in humans is presently unknown. In the present study, 112 workers were selected and divided into four groups on the basis of their level of occupational exposure to benzene: a control group, two groups of workers exposed to either low (< 300 mg/m3) or high concentrations of benzene (> 300 mg/m3) and a group of workers who had experienced benzene poisoning. Blood samples from these workers were assayed for the number of peripheral white blood cells, concentration of hemoglobin, activities of serum superoxide dismutase (SOD), lymphocyte DNA damage and finally for the presence of antibodies to different human heat-shock proteins (Hsp27, Hsp60, Hsp71 and Hsp90). Benzene-poisoned workers showed a high incidence of antibodies against Hsp71 (approximately 40%) which was associated with a decrease in white blood cells (3.84+/-1.13 x 10(9)versus 7.68+/-1.84 x 10(9) in controls) and with an increase in activities of serum SOD (138.43+/-23.15 micro/ml) and lymphocyte DNA damage (18.7%). These data suggest that antibodies against Hsps can potentially be useful biomonitors to assess if workers are experiencing or have experienced abnormal xenobiotic-induced stress within their living and working environment.

Adult↗
PubMed1998

Genetic identification and management of hereditary nonpolyposis colorectal cancer.

Hereditary nonpolyposis colorectal cancer (HNPCC) is a syndrome involving a predisposition to cancers of the colon, endometrium and several other extra-colonic sites, accounting for approximately 1-5% of all colorectal cancer cases. It is not easily recognized because of a lack of distinctive clinical markers, making diagnosis and management of this disease problematic. To provide a basis for uniformity in diagnosis of HNPCC, the Amsterdam criteria were proposed and are currently in use. More recently, the discovery of four human mismatch repair genes (hMSH2, hMLH1, hPMS1 and hPMS2) has provided novel insight into the genetic basis of this disease, and raised the possibility of genetic diagnosis for management of HNPCC patients and their family members. This report summarizes the clinicopathologic aspects of HNPCC, reviews the recent genetic findings and surveillance strategies, and suggests a novel designation of certain patients as suspected HNPCC.

Colorectal Neoplasms, Hereditary Nonpolyposis↗
PubMed1998

A neural network for the optimization of fed-batch glutamic acid production.

A neural network system, which is composed of a simulation subnetwork and an optimization subnetwork, was constructed to predict and optimize the industrial fed-batch fermentation of glutamic acid. A data-compression and filtration network structure was incorporated into the simulation subnetwork to extract "noise-free" patterns from the input signals. The sole-variant optimization and the multiple-variant optimization can be easily carried out by the neural network developed. A satisfactory result has been achieved.

Computer Simulation↗
PubMed1998

Experimental study on intramuscular injection of eukaryotic expression vector pcDNA3- IL-6 on BXSB mice.

OBJECTIVE: To study the role of IL-6 in systemic lupus erythematosis (SLE). METHODS: We constructed eukaryotic expression vector pcDNA3- IL-6 encoding for IL-6 and injected it intramuscularly into BXSB mice. 22 of the 3.5-month-old male BXSB mice were divided into two groups. One group was injected with the pcDNA3-IL-6 100 micrograms per mouse twice at the interval of 20 days. Another group was injected with plasmid pcDNA3 at the same time as control. The ANA and proteinuria were monitored every 10 days, and the IL-6 activity in serum, IgG, C3 deposition and IL-6 expression in kidney detected at the 40th day. RESULTS: IL-6 encoding plasmid had harmful effects on murine SLE with increased ANA level, proteinuria, IgG, C3 deposition and IL-6 expression in kidney, but there was no difference of serum GPT levels between the two groups. CONCLUSION: Excessive production of IL-6 could play an important pathogenic role in SLE. Blocking or reducing IL-6 secretion might be a new therapy for SLE.

Animals↗
PubMed1998

Objective evaluation of oral and maxillofacial sensory nerves.

OBJECTIVE: The purpose of this article is to recommend a set of methods for the clinical objective evaluation of neurosensory nerves and to establish criteria for the clinical objective evaluation of oral and maxillofacial regions in a Chinese population. METHODS: Sensations in the oral and maxillofacial regions of 35 healthy subjects were objectively and quantitatively evaluated by means of two-point discrimination, static light touch, brush directional stroke, and thermal discrimination. RESULTS: Criteria for the clinical neurosensory evaluation were established for the sensations of the oral and maxillofacial regions of healthy Chinese. CONCLUSIONS: Two-point discrimination, static light touch, brush directional discrimination, and thermal discrimination can provide objective, quantitative information for the evaluation of sensory nerve impairment. These convenient methods represent the important tools in the diagnosis and treatment of sensory nerve impairment in oral and maxillofacial regions.

Adolescent↗
PubMed1998

[The relation between nutrition and pulmonary ventilation in patients with chronic obstructive pulmonary disease during the relieved period].

To observe the effect of nutrition on pulmonary ventilation in aged patients with chronic obstructive pulmonary diseace (COPD) during the relieved period, the pulmonary function (MVV, PVC, FEV1, MMEF) of 261 aged patients with COPD was tested during the relieved period. The results showed that the MVV (48.75% +/- 19.9%) tested in the patients with malnutrition was significantly lower than that tested in the patients with normal nutrition (59.1% +/- 22.6%) (P < 0.01) while there was no marked difference in the ventilation in their large and small airway. It is conluded that malnutrition of the patients with COPD affects the constrictive function of respiratory muscle and thus results in a decrease in MVV.

Aged↗
PubMed1998

[Respiratory muscle function and serum enzymology in hyperthyroidism before and after treatment].

To investigate the effect of hyperthyroidism on respiratory muscle function and its possible mechanism, the thyroid function, serum enzymology, serum potassium, pulmonary function and respiratory muscle function were examined in 60 patients with Grave's disease before treatment and 26 patients among them after treatment, and 20 normal subjects as control. T3, T4, and FT4 increased while FVC and PImax, which reflect the respiratory muscle strength, and Pi/PImax, which reflects the reserve capacity of inspiratory muscle, decreased significantly in the 60 patients with Grave's disease, compared with the ones of normal subjects. The comparison of above measurements in the 26 patients between before- and after-treatment showed that respiratory muscle strength increased obviously along with the improvement of throid function. The serum enzymology, potassium and TSH, however, were not abnormal and not changed after treatment. The thyroid functions in 10 patients with hyperthyroid heart disease were not different, compared with the ones of other 50 patients without hyperthyroid heart disease, but their respiratory muscle strength was significantly lower than the ones of latter. The above results suggested that hyperthyroidism could lead to significant decrease of respiratory muscle strength and its reserve capacity, whereas treatment for hyperthyroidism would improve respiratory muscle function, so the measurement of respiratory muscle function in hyperthyroidism cases might be useful in prediction of hyperthyroid heart disease.

Adult↗
PubMed1998

[Inhibition of apoptosis by bcr-abl fusion gene in K562 cells].

OBJECTIVE: To investigate the effect of bcr-abl fusion gene on CML cell apoptosis. METHODS: Apoptosis of in vitro cultured K562 cells was observed after exposure to synthetic 18-mer antisense oligodeoxynucleotide complementary to the bcr-abl junction (b3a2). RESULTS: Apoptosis of K562 cells was significantly increased associated with inhibition of bcr-abl expression. CONCLUSION: bcr-abl fusion gene formation due to chromosome translocation may be the major mechanism of CML via inhibition of apoptosis.

Apoptosis↗
PubMed1998

[Study on expression of IRF-1 gene in human leukemia with RT-PCR and the silver sequence techniques].

OBJECTIVE: To explore preliminarily the changes of IRF-1 gene expression in leukemias. METHODS: The expression of IRF-1 gene in 24 leukemia patients and 3 leukemic cell lines were studied with RT-PCR and the silver sequence techniques. RESULTS: No expression of IRF-1 gene in 3 patients, and significantly decreased expressions in 5 patients and in HL-60 and HIMeg cell lines were revealed. CONCLUSION: The mechanism of human leukemogenesis may be partly associated with no or low-expression of IRF-1 gene.

DNA-Binding Proteins↗
PubMed1998

[Clinical study of uvulopalatopharyngoplasty treatment for obstructive sleep apnea syndrome].

In order to investigate the treatment of obstructive sleep apnea syndrome (OSAS), we have performed uvulopalatopharyngoplasty (UPPP) operations on 60 cases. The clinical results showed that 50.0 percent of the operated patients somewhat improved and 16.7 percent unimproved. The total success rate was 83.3%. The key ways; 1. Proper indication; 2. Using local anaesthesia rather than general anaesthesia; 3. Intraoperative monitor ECG, blood pressure and oxygen saturation; 4. Preoperative physician consultation if patients complicated with cardiopulmonary problems. UPPP is one of the effective methods to treat OSAS, especially for OSAS with stricture in pharyngeal cavity. It has less damage, less operative complications and so on.

Adult↗
PubMed1998

[Determination of tranilast in human plasma by reversed-phase high performance liquid chromatography and its pharmacokinetics].

A simple and rapid method for the determination of tranilast in human plasma by RP-HPLC is described. The analytical column was packed with YWG-C18. The mobile phase consisted of methanol-0.02 mol/L KH2PO4(60:40, V/V; pH 4.2), and detected by UV detector at a wavelength of 333 nm. The plasma sample was injected directly into the HPLC system after precipitation of the protein with methanol. The calibration curve was linear within the concentration range of 0.625-40 mg/L. The average recovery was 100.0% +/- 4.1%, and minimum detectable concentration was 0.2 mg/L. By using this method, the pharmacokinetics of tranilast in the plasma of ten healthy volunteers after oral administration of 200 mg drug were studied. The plasma drug concentration-time curve of volunteers conforms to one-compartment open model.

Anti-Allergic Agents↗
PubMed1998

[Determination of uric acid, creatinine and pseudouridine in human urine by high performance capillary zone electrophoresis].

A simultaneous determination of uric acid, creatinine and pseudouridine in human urine by high performance capillary zone electrophoresis(HPCZE) is described. The urine samples were refrigerated and filtered. Then the samples were directly introduced into the capillary and a phosphate buffer solution(pH 6.1) was employed. The capillary used was 36 cm x 50 microns i.d. and detection was carried out with a UV monitor at 210 nm. The calibration curve showed a good linearity for uric acid, creatinine, and pseudouridine in the concentration range of 2-80 mg/L and their correlation coefficients were 0.996, 0.996 and 0.999 respectively. Within day CV for assaying the urine samples of uric acid, creatinine and pseudouridine were 5.0%, 3.0%, and 4.4%, and the corresponding between day data were 6.5%, 5.9%, and 5.3%, respectively. The recoveries of uric acid, creatinine and pseudouridine were 99.0%, 102.%, 92.2%, respectively. The total time for separation and determination was within 10 min. This method is characterized by direct assay of urine samples without any pretreatment. The results show that HPCZE is a simple, rapid, sensitive and reliable assay method.

Creatinine↗