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Biomedical subjects

Y Yuan

Publications and source records attributed to Y Yuan.

At least 199 records · Page 11Linked to original sources
PubMed1997

[Total knee replacement in diabetic patients].

From December 1987 to March 1995, 16 TKRs were performed for 9 diabetic patients at our department. 7 of them had rheumatoid arthritis (RA), and 2 osteoarthritis (OA). There were 1 male and 8 females. The average age was 55.9 years (range 49-69 years), and the average weight was 64.5 kg (range 54-78 kg). According to the hospital for special surgery (HSS) knee rating scale, the pre and postoperative evaluations were made. The HSS scores were improved after the operation from average 30.2 points preoperatively to 78.2 points postoperatively. The excellent and good rate was 94%. After 3.9 years follow-up (range 10 months to 8 years), the HSS score was 74.4 points, and the rate of excellent and good was 87.5%. Compared to the other 209 RA or OA patients with 287 TKR at the same period, the HSS score was almost the same, but the infection rate was higher (3.5%). We conclude that the TKR of diabetic patients could also get the similar results as common patients if the patients are under the good control of glycemia and medical treatment.

Aged↗
PubMed1997

[Prognosis prediction of S-phase fraction and p53, c-erbB-2, estrogen receptor, progesterone receptor in axillary node-negative breast cancer].

The prognostic factors in 180 axillary node-negative breast cancer patients with more than 5 year follow-up were searched for with multiple regression. Based on the regression results, the cases with treatment failure in 5 year and the cases with 5 year disease free survival were matched at 1:2 ratio. Then the c-erbB-2 protein, p53 Protein, estrogen receptor (ER), progesterone receptor (PR) and the S-phase fraction (SPF) were measured in paraffin-embedded breast cancer tissue. The results were analysed with log-rank test and Cox-Model. Among the biobehaviour factors measured, the SPF was the strongest prognosis predictor for ANN. The 5 year disease free survival rate of ANN with SPF < 10% or > 10% was 94% and 52% respectively (P < 0.001). The treatment failure relative risk of patients with SPF > 10% ANN was 11.31. The relative risk of other four factors was respectively, PR 3.58 (P < 0.002), ER 2.93 (P < 0.05), p53 1.44 (P > 0.3), c-erbB-2 1.38 (P > 0.5). The combination of PR or EP with SPF could make the relative risk even higher.

Axilla↗
PubMed1997

[Measurement and clinical significance of inspiratory drive efficacy in patients with chronic obstructive pulmonary disease].

To study the relationship between VT/P0.1 and the function of inspiratory muscles, we performed the measurement of VT/P0.1 (inspiratory drive efficacy), MIP (maximal inspiratory mouth pressure) and MMIF (maximal midinspiratory flow) in 15 normal subjects and 60 patients with chronic obstructive pulmonary disease(COPD). The results indicated that VT/P0.1 decreased with the deterioration of COPD and it correlated highly and positively with MIP and MMIF. These suggest that VT/P0.1 can reflect the function of inspiratory muscles as well as MIP and MMIF can.

Aged↗
PubMed1997

[Effect of methylphenidatum on inspiratory muscles function in patients with chronic obstructive pulmonary disease and its mechanism].

To have a better understanding of the effect of methylphenidatum on inspiratory muscles function, we studied the respiratory force parameters of 70 patients with chronic obstructive pulmonary disease by intravenous infusion methylphenidatum in a randomized controlled clinical trial. The indices of respiratory force parameter included maximal inspiratory mouth pressure (MIP), maximal midinspiratory flow (MMIF), forced inspiratory capacity (FIC), maximal works of inspiration (Wimax) and airway occlusion pressure (P0.1), etc. Aminophylline and Nikethamidi were chosen as controls. The results showed that MIP, MMIF, FIC, Wimax, P0.1 and minute ventilation (Vr) were significantly increased after administration of methylphenidatum and aminophylline. There were no significant differences in MIP, MMIF, FIC and Wimax after administration of Nikethamidi, but P0.1 was significantly increased and the increase was higher than that after administration of methylphenidatum and aminophylline groups. We conclude that methylphenidatum can significantly improve the function of inspiratory muscles as aminophylline can do.

Female↗
PubMed1997

[Immunologically prepared plasma specimen of albuterol for high performance liquid chromatographic determination].

Immune-affinity method for preparation of sample in plasma is reported in this paper. Albuterol was coupled to bovine serum albumin (BSA) to prepare the antigen and immunized in rabbit to produce the anti-albuterol serum (immune globulin). The anti-albuterol serum was treated with saturated ammonium sulfate solution to obtain the antibody (immune globulin). The antibody was coupled with Sepharose 4B to prepare the immune globulin-affinity column. The plasma containing albuterol was introduced into the column and was rinsed in turn with phosphate buffer and water, and then eluted with methanol. After being concenfrated the sample was analyzed by HPLC with a sillica column (4.6 mm x 200 mm, 5 microm), a mixture of methanol: 2 mol/L ammonium acetate (99.5 : 0.5) as mobile phase with a flow rate of 1.2 mL/min, and fluorecence detector monitoring at lambdaex = 226 nm and lambdaem = 306 nm. The results showed that the immune globulin-affinity column has the characteristic of high purity and high specificity, and it is suitable for the preparation of chromatographic plasma specimen to determine albuterol in plasma. The relationship between peak area ratios and concentration from 2 to 80 microg/L were linear (r=0.998). The extraction recoveries from plasma at concentrations of 2-80 microg/L were 98.8% +/- 7.3%. The RSD for intra-day (n=5) was 5.8% and that for inter-day assay (n=5) was 7.8%.

Albuterol↗
PubMed1997

[HPLC determination of diltiazem in human serum and its pharmacokinetic parameters].

A simple and sensitive reversed-phase liquid chromatographic method has been developed and validated for the analysis of diltiazem in human serum and the study of pharmacokinetics of the drug in human body. Diltiazem and diazepam (internal standard) in serum were extracted with hexane-chloroform-isopropanol (60:40:5, V/V), and then measured by HPLC using a Spherisorb C18 column as stationary phase and a methanol-water triethylamine as mobile phase. Diltiazem was quantified by ultraviolet absorbance at 239 nm. The method proved to be linear in the clinical range of 15-300 microg/L with a regression coefficient of 0.9997. The lower limit of detection of diltiazem in serum was 3 microg/L. Intra-day and inter-day coefficients of variation of assay for diltiazem in serum were 3.5%-6.8% (n=7) and 6.2%-8.4% (n=5), respectively. The recoveries of diltiazem were 91%-104% for serum. The method has been used to determine diltiazem in serum samples from eight volunteers and provided data on the pharmacokinetics of the drug. The results inferred that diltiazem is absorbed rapidly and had a relatively short half-life time in healthy individuals. The data obtained was fitted with PKBP-N1 program on computer to study the pharmacokinetics. The results showed that the peak level in serum averaged 118.5 microg/L +/- 14.3 microg/L at 3.1 h +/- 0.4 h, and the areas under the drug concentration curves (AUC) was 793.1 microg x h/L +/- 83.1 microg x h/L.

Antihypertensive Agents↗
PubMed1997

Adverse reactions to food constituents: allergy, intolerance, and autoimmunity.

Food allergies and intolerance represent important health concerns to consumers who are predisposed to these illnesses. Unlike many current food safety issues, food sensitivities are complicated by both complex and multiple individual adverse reactions, which can vary from emotional to pathophysiological ailments. In some instances, the underlying mechanisms that result in the development of food allergies or intolerance have marked differences but produce common symptoms. The present-day diagnosis of these disorders can be impeded by intrinsic limitations in generating accurate information from patient history and biochemical, physicochemical, and immunochemical tests. Oral challenge tests represent effective methods for confirming and testing food allergens and food intolerance; however, these procedures are often restricted to clinical trials. It is important to be able to distinguish among food allergy, intolerance, and autoimmune disease in the management of these disorders. The role of food in the development of autoimmune disease may be exemplified by celiac disease, a food-induced enteropathy, requiring exposure to prolamins in wheat, rye, and barley. Various wheat and soy protein sources, including the soy protein isolates used to make infant formulas, have been related to juvenile or insulin-dependent diabetes mellitus (IDDM), a common chronic disease of childhood. Employing food process technologies to eliminate food constituents with potential for intolerance in some individuals is a potentially viable approach for reducing risk to food-related disorders. Finally, the development of food labelling regulations that require the identification of potential food allergens or agents for intolerance in the ingredient declaration on prepackaged food is a positive step toward the prevention of severe adverse reactions in hypersensitive individuals.

Animals↗
PubMed1997

Action of methylmercury on GABA(A) receptor-mediated inhibitory synaptic transmission is primarily responsible for its early stimulatory effects on hippocampal CA1 excitatory synaptic transmission.

Bath application of methylmercury (MeHg) causes an early stimulation before block of synaptic transmission in the CA1 region of hippocampal slices. Effects of MeHg and Hg++ on inhibitory postsynaptic potentials (IPSPs) or currents (IPSCs) and excitatory postsynaptic potentials (EPSPs) or currents (EPSCs) were compared to test whether or not early block by MeHg of GABA(A)-mediated inhibitory synaptic transmission and MeHg-induced alterations of the resting membrane potentials of CA1 neurons contribute to this initial enhancement of excitability. MeHg affected IPSPs and IPSCs similarly, and more rapidly than EPSPs and EPSCs. In contrast, although Hg++ blocked IPSPs more rapidly than EPSPs, times to block of IPSCs and EPSCs by Hg++ were virtually identical when CA1 neurons were voltage-clamped at their resting membrane potential levels. MeHg increased EPSC amplitudes before their subsequent decrease even when CA1 neuronal membranes were voltage-clamped at their resting potentials. This suggests that effects of MeHg on CA1 cell membrane potentials are not a major factor for MeHg-induced early stimulation of hippocampal synaptic transmission. Effects of MeHg and Hg++ on the reversal potentials for IPSCs also differed. Both metals blocked all outward and inward currents generated at different holding potentials. However, MeHg shifted the current-voltage (I/V) relationship to more positive potentials, although Hg++ shifted the I/V curve to more negative potentials. Hg++ was a less potent blocker of on IPSCs and EPSPs or EPSCs than was MeHg. To determine if the early increase in amplitude of population spikes or EPSPs is due to an action of MeHg at GABA(A) receptors, extracellular recordings of population spikes and intracellular recordings of EPSPs were compared with or without pretreatment of hippocampal slices with bicuculline. After preincubation of slices with 10 microM bicuculline for 30 to 60 min, MeHg only decreased the amplitudes of population spikes and EPSPs to block; no early increase of synaptic transmission occurred. Pretreatment of slices with strychnine, did not prevent MeHg-induced early increase in population spikes. MeHg also blocked responses evoked by bath application of muscimol, a GABA(A) agonist. Thus, block by MeHg of GABA(A) receptor-mediated inhibitory synaptic transmission may result in disinhibition of excitatory hippocampal synaptic transmission, and appears to be primarily responsible for the initial excitatory effect of MeHg on hippocampal synaptic transmission.

Animals↗
PubMed1997

[Relative contribution of ageing and menopause to the changes of lumbar bone density in 1,400 Beijing women].

OBJECTIVE: To study the pattern of bone mass changes in women's lumbar spine and obtain evidence to guide the prevention of postmenopausal osteoporosis. METHOD: Bone mineral content (BMC) and bone mineral density (BMD) of lumbar 1-4 in 1 400 Beijing women aged 20-85, were measured by dual energy X-ray absorptiometry. RESULTS: (1) Both BMC and BMD increased after age 20, reached the peak at the age of 30, and decreased significantly after the age of 50; (2) There was no significant change of BMC and BMD after the age of 25 in premenopausal women. Bone loss accelerated in the first 10 years after menopause. Women who experienced menopause early had lower bone mass. (3) The prevalence of osteoporosis in 1 121 postmenopausal women was 17.40%. CONCLUSION: Significant bone mass loss of lumbar spine occurs during the first decade following menopause, which is the key period for preventing osteoporosis.

Adult↗
PubMed1997

[The reversion of multidrug resistance in tumour cell line MCF-7/Adr by ribozyme].

OBJECTIVE: To construct a specific hammerhead ribozyme possessing catalytic activity that cleaves the mdr1 mRNA for reversing the resistant phenotype in tumour cell line. METHODS: A DNA sequence encoding the ribozyme gene was incorporated into a eukaryotic expression vector (pH beta Apr-1 neu) and transfected into the human breast carcinoma cell line MCF-7/Adr, which is resistant to adriamycin and expresses the MDR phenotype. RESULTS: The ribozyme was stably expressed in the cell line, and decreased the level of mdr1 mRNA expression by 83.5%. The ribozyme inhibited the formation of P-glycoprotein and reduced the cell's resistance to adriamycin. CONCLUSION: The resistant cells were 1,000-fold more resistant than the parental cell line (MCF-7), whereas those cell clones that showed ribozyme expression were only 6-fold more resistant than the parental cell line.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

A common mechanism for the biosynthesis of methoxy and cyclopropyl mycolic acids in Mycobacterium tuberculosis.

Mycobacterium tuberculosis produces three classes of mycolic acids that differ primarily in the presence and nature of oxygen-containing substituents in the distal portion of the meromycolate branch. The methoxymycolate series has a methoxy group adjacent to a methyl branch, in addition to a cyclopropane in the proximal position. Using the gene for the enzyme that introduces the distal cyclopropane (cma1) as a probe, we have cloned and sequenced a cluster of genes coding for four highly homologous methyl transferases (mma1-4). When introduced into Mycobacterium smegmatis, this gene cluster conferred the ability to synthesize methoxymycolates. By determining the structure of the mycolic acids produced following expression of each of these genes individually and in combination, we have elucidated the biosynthetic steps responsible for the production of the major series of methoxymycolates. The mma4 gene product (MMAS-4) catalyzes an unusual S-adenosyl-L-methionine-dependent transformation of the distal cis-olefin into a secondary alcohol with an adjacent methyl branch. MMAS-3 O-methylates this secondary alcohol to form the corresponding methyl ether, and MMAS-2 introduces a cis-cyclopropane in the proximal position of the methoxy series. The similarity of these reactions and the enzymes that catalyze them suggests that some of the structural diversity of mycolic acids results from different chemical fates of a common cationic intermediate, which in turn results from methyl group addition to an olefinic mycolate precursor.

Amino Acid Sequence↗
PubMed1996

The bioactive phospholipid, lysophosphatidylcholine, induces cellular effects via G-protein-dependent activation of adenylyl cyclase.

The naturally occurring phospholipid, lysophosphatidylcholine (lyso-PC), regulates a broad range of cell processes, including gene transcription, mitogenesis, monocyte chemotaxis, smooth muscle relaxation, and platelet activation. Despite the growing list of cellular effects attributable to lyso-PC, the mechanism(s) by which it alters cell function have not been elucidated. In this report, we have examined the effects of exogenous lyso-PC on signal transduction processes within a variety of lyso-PC-responsive cells, including human platelets, monocyte-like THP-1 cells, and the megakaryoblastic cell line, MEG-01. Pretreatment of each of these cells with increasing concentrations of lyso-PC (25-150 microg/ml) was associated with a progressive increase in the cytosolic concentration of cAMP. The accumulation of cAMP in platelets correlated closely with the ability of lyso-PC to inhibit multiple platelet processes, including platelet aggregation, agonist-induced protein kinase C activation, thromboxane A2 generation, and the tyrosine phosphorylation of platelet proteins. In each of the cell types examined, the ability of lyso-PC to increase the cellular levels of cAMP was synergistically enhanced by pretreating the cells with the cAMP phosphodiesterase inhibitor, theophylline (5 mM), and was specifically inhibited by the P-site inhibitor of adenylyl cyclase, 2,5-dideoxyadenosine. A role for the stimulatory G-protein, Gs, in the lyso-PC-induced activation of adenylyl cyclase was suggested by the ability of the GTPase inhibitor, guanylyl 5'-thiophosphate (0.2 mM), to inhibit the lyso-PC-stimulated increase in cAMP, and also by the ability of cholera toxin to inhibit increases in membrane GTPase activity in response to lyso-PC. The functional significance of lyso-PC-induced activation of adenylyl cyclase was investigated in MEG-01 cells. Treatment of these cells with either lyso-PC or dibutyryl cAMP for 36-40 h resulted in a 3-5-fold increase in the surface expression of the natural anticoagulant protein, thrombomodulin (TM). The ability of lyso-PC to increase TM expression was abolished by pretreating these cells with the adenylyl cyclase inhibitor, 2,5-dideoxyadenosine, whereas the dibutyryl cAMP-induced increase in TM remained insensitive to adenylyl cyclase inhibition. These studies define an important role for the adenylyl cyclase signaling system in mediating cellular effects induced by lyso-PC.

Adenylyl Cyclases↗
PubMed1996

Focal adhesion kinase (pp125FAK) cleavage and regulation by calpain.

Focal adhesion kinase (125 kDa form; pp125FAK) is a widely expressed non-receptor tyrosine kinase that is implicated in integrin-mediated signal transduction. We have identified a novel means of pp 125FAK regulation in human platelets, in which this kinase undergoes sequential proteolytic modification from the native 125 kDa form to 90, 45 and 40 kDa fragments in thrombin-, collagen- and ionophore A23187-stimulated platelets. The proteolysis of pp125FAK was prevented by pretreating platelets with the calpain inhibitors calpeptin or calpain inhibitor-1, and was reproduced in vitro by incubating immunoprecipitated pp125FAK with purified calpain. Proteolysis of pp125FAK resulted in a dramatic reduction in its autokinase activity and led to its dissociation from the cytoskeletal fraction of platelets. These studies define a novel signal-terminating role for calpain, wherein proteolytic modification of pp125FAK attenuates its autokinase activity and induces its subcellular relocation within the cell.

Blood Platelets↗
PubMed1996

[Giant axonal neuropathy. A case report].

We report a sporadic case of giant axonal neuropathy (GAN) starting in a 5-year-old boy with gait disturbance. At the age of 10 years he showed signs of a sensomotoric polyneuropathy and central neurological symptoms: intention tremor, nystagmus and visual disturbance. The boy also had curly hair. Sural nerve biopsy showed many giant axons with accumulation of microfilaments, which were also found in cytoplasma of Schwann cells, endothelial cells and fibrocytes. Similar changes were detected in endothelial cells of a muscle biopsy, which additionally displayed neurogenic atrophy and target fibers. Immunohistochemically, desmin, vimentin, heat shock protein 70, and ubiquitin were not detectable in giant axons, which, however, contained neurofilament protein 68, 200 and beta-tubulin. Our case shows that careful ultrastructural examination of a muscle biopsy may point to the diagnosis of GAN.

Axons↗
PubMed1996

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL): a morphological study of a German family.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is characterized clinically by recurrent cerebral infarcts, subcortical dementia and pseudobulbar palsy, and morphologically by a granular degeneration of cerebral and, to a lesser degree, extracerebral blood vessels. We present morphological findings in a further German family affected by CADASIL. The index case showed the typical periodic acid-Schiff-positive granular degeneration of vascular smooth muscle cells (VSMC) in cerebral vessels, which did not react with antibodies against various immunoglobulins or complement factors. Ultrastructurally, granular osmiophilic material (GOM) covered the VSMC in different cerebral regions as well as in extracerebral organs (muscle, nerve, skin, small and large intestine, liver, kidney and heart). Skin biopsy samples from other family members of the last two generations also revealed GOM irrespective of the clinical symptomatology (CADASIL, migraine only or asymptomatic). Patients in the third generation had higher amounts of GOM in skin vessels than did asymptomatic or migraine patients in the fourth generation. We conclude that skin biopsy is a useful and less invasive screening method for the differential diagnosis of CADASIL.

Adult↗
PubMed1996

A poroelastic finite element formulation including transport and swelling in soft tissue structures.

A field theory is presented for the study of swelling in soft tissue structures that are modeled as poroelastic materials. As a first approximation, soft tissues are assumed to be linear isotropic materials undergoing infinitesimal strains. Material properties are identified that are necessary for the solution of initial boundary value problems where swelling and convection are significant. A finite element model is developed that includes the solid displacements, the relative fluid displacements, and a representative concentration as the primary unknowns. A numerical example is presented based on a triphasic model. The finite model simulates a typical experimental protocol for soft tissue testing and demonstrates the interaction and coupling associated with relative fluid motion and swelling in a deforming poroelastic materiaL The theory and finite element model provide a starting point for nonlinear porohyperelastic transport-swelling analyses of soft tissue structures that include finite strains in anisotropic materials.

Algorithms↗