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Biomedical subjects

S Liao

Publications and source records attributed to S Liao.

At least 37 records · Page 2Linked to original sources
PubMed2001

Aortic and mitral valve replacement with retrograde perfusion in the beating heart.

OBJECTIVE: To estimate the value of aortic valves and combined mitral valve replacement with retrograde perfusion in beating hearts. METHODS: Continuous retrograde coronary sinus perfusion with beating hearts was used in 83 patients undergoing aortic valve or aortic valve combined with mitral valve replacement, without application of cardioplegia. After aortic valve replacement, the retrograde perfusion was changed to antegrade perfusion for mitral valve replacement or correction of the other deformities (group A). Cold blood cardioplegia solution (15 degrees C) was infused at intervals in 20 cases (group B). The following parameters were tested: lactate, ET, CTn-T and MDA in blood; myocardial ultra-structure; and cardiac rhythm and cardiac output (CO). RESULTS: All biochemical values increased after cardiopulmonary bypass (P < 0.05-0.01). Empty and beating heart sinus rhythm was maintained in group A. Myocardial ultrastructure did not change significantly. The pump was stopped smoothly as the surgical procedure finished. No postoperative low cardiac output syndrome or arrhythmia was observed. Eight-one patients recovered smoothly, two died from renal failure or infective shock. When the pump stopped, all patients in group B were supported by 5-10 micrograms.kg-1.min-1 dopamine. Transient pacing was used in 9 patients. One patient died from low cardiac output syndrome. CONCLUSION: This method is a good myocardial protection which simulates physiologic status. It is applicable to aortic valve and combined mitral valve replacement of patients with large heart or heart failure and long time aortic cross-clamping. Ideal clinical effect can be achieved.

Adolescent↗
PubMed2001

The medicinal action of androgens and green tea epigallocatechin gallate.

Unorthodox (non-traditional or alternative) medicinal practices have been expanding very rapidly in western countries. Modern physicians, scientists, and non-traditional medicine practitioners now must join forces to promote evidence-based medicine to benefit patients. Green tea extracts are among the most widely used ancient medicinal agents, while androgens are probably the oldest drugs used in a purified form in traditional Chinese medicine. It is now clear that a specific green tea catechin, (-)epigallocatechin-3-gallate, can modulate the production and biological actions of androgens and other hormones. Modulation of androgenic activity and administration of (-)epigallocatechin-3-gallate may be useful for the treatment of various hormone-related abnormalities, such as benign prostatic hyperplasia, baldness, and acne, as well as androgen-dependent and -independent prostate cancers. (-)Epigallocatechin-3-gallate has also been shown to modulate appetite and control obesity in animals.

Androgens↗
PubMed2001

[Pulmonary hyalinizing granuloma: a case report and a review of the literature].

OBJECTIVE: To highlight the characteristics of pulmonary hyalinizing granuloma (PHG). METHOD: One patient with PHG confirmed by pathological assessment was presented and relevant literatures were reviewed. RESULTS: PHG is a rare disease characterized by multiple bilateral pulmonary nodules. Symptoms include cough, dyspnea, chest pain, hemoptysis, fever and fatigue. Histologically, the nodules consist of haphazard or whorled arrays of lamellar, keloid - like collagen. Evidence suggests that the nodules are the result of a chronic exaggerated immune response. CONCLUSIONS: PHG should be considered in patients showing multiple bilateral pulmonary nodules. The clinical course of PHG in most patients is benign. At present, there is no effective therapy.

Fatal Outcome↗
PubMed2000

The function of Xenopus Bloom's syndrome protein homolog (xBLM) in DNA replication.

The Bloom's syndrome gene (BLM) plays a pivotal role in the maintenance of genomic stability in somatic cells. It encodes a DNA helicase (BLM) of the RecQ family, but the exact function of BLM remains elusive. To study this question, we have cloned the BLM homolog of the frog Xenopus laevis (xBLM) and have raised antibodies to it. Immunodepletion of xBLM from a Xenopus egg extract severely inhibits the replication of DNA in reconstituted nuclei. Moreover, the inhibition can be rescued by the addition of the recombinant xBLM protein. These results provide the first direct evidence that BLM plays an important role in DNA replication, suggesting that Bloom's syndrome may be the consequence of defective DNA replication.

Adenosine Triphosphatases↗
PubMed2000

A three-dimensional model of the delta-opioid pharmacophore: comparative molecular modeling of peptide and nonpeptide ligands.

A comparative molecular modeling study of delta-opioid ligands was performed under the assumption that potent peptide and nonpeptide agonists may have common three-dimensional (3D) arrangement of pharmacophore groups upon binding to the delta-receptor. Low-energy conformations of the agonists 7-spiroindanyloxymorphone (SIOM) and 2-methyl-4a-alpha-(3-hydroxyphenyl)-1,2,3,4,4a,5,12, 12a-alpha-octahydro-quinolino[2,3,3-g]isoquinoline (TAN-67), and a partial agonist oxomorphindole (OMI) were determined by high-temperature molecular dynamics (MD). A good spatial overlap was found for the pharmacophore groups of SIOM, TAN-67, and OMI, including the basic nitrogen, phenol hydroxyl, and two aromatic ring. Based on this overlap we proposed a 3D pharmacophore model for nonpeptide delta-opioid agonists with a distance of 7.0 +/- 1.3 A between the two aromatic rings and of 8.2 +/- 1.0 A between the nitrogen and phenyl ring. The potent and highly delta-opioid receptor selective agonist [(2S,3R)-TMT(1)]DPDPE, which shares global backbone constraints of the 14-membered disulfide cycle and a strong preference for the trans rotamer of the TMT(1) side chain, was chosen as a peptide template of the delta-opioid pharmacophore. Extensive MD simulations at 300 K with the AMBER force field were performed for [(2S,3R)-TMT(1)]DPDPE and the less potent [(2S, 3S)-TMT(1)]DPDPE analogue. Multiple MD trajectories were collected for each peptide starting from the x-ray structures of DPDPE and [L-Ala(3)]DPDPE and from models proposed in the literature. Low-energy MD conformations were filtered by the nonpeptide pharmacophore query and then directly superimposed with SIOM, OMI, and TAN-67. Two conformers of [(2S,3R)-TMT(1)]DPDPE that showed the best overlap with the nonpeptide pharmacophore (rms deviation </= 1. 0 A for N,O atoms and centroids of two aromatic rings) were selected as possible delta-receptor binding conformations. These conformations have similar backbone structures, and trans rotamers of the TMT(1) side-chain group. They are reasonably close to the crystal structure of [L-Ala(3)]DPDPE, and differ significantly from the crystal structure of DPDPE. The conformer with a gauche(-) rotamer of Phe(4) is most consistent with structure-activity relationships of delta-opioid peptides. The proposed 3D models were used for rational design of new nonpeptide delta-receptor ligands.

Analgesics↗
PubMed2000

Accelerated replicative senescence of medial smooth muscle cells derived from abdominal aortic aneurysms compared to the adjacent inferior mesenteric artery.

BACKGROUND: Abdominal aortic aneurysms (AAAs) are associated with aging and atherosclerosis. AAAs arise through a degenerative process characterized in part by depletion of medial smooth muscle cells (SMC), suggesting that generalized aging and SMC senescence represent potential mechanisms contributing to aneurysmal degeneration. It is not yet known whether SMC from AAA tissue exhibit a difference in proliferative capacity compared to SMC from nonaneurysmal vessels or to what extent such differences might be due to aging alone or other patient-specific factors. MATERIALS AND METHODS: Aneurysm wall tissues were obtained from 15 patients undergoing AAA repair. In each case, a segment of the adjacent (nonaneurysmal) inferior mesenteric artery (IMA) from the same patient was used as a control. Paired AAA- and IMA-derived SMC strains were obtained by explant techniques and their proliferative capacities were compared during serial passage in culture. RESULTS: Sustainable SMC cultures were established from all IMA explants but from only 9 of 15 AAAs (P < 0.05). The interval required to achieve primary explant growth was longer for AAAs than IMAs (16.4 +/- 2 vs 6.4 +/- 1 days; P < 0.001), but it was unrelated to patient age, gender, or aneurysm size. AAA-derived SMC appeared larger and rounder than the corresponding IMA-derived SMC, even after repeated passage in culture, and their maximal proliferation was reduced by 44.2 +/- 8% (n = 5 pairs, P < 0.05). Serum-stimulated [(3)H]thymidine uptake in AAA-derived SMC was also reduced by 54.9 +/- 7% (n = 5 pairs, P < 0.01), but flow cytometry revealed no differences in SMC viability, apoptosis, or necrosis. While IMA-derived SMC continued to proliferate beyond passage 20 during serial subculture, all AAA-derived SMC developed replicative senescence by passage 12. CONCLUSIONS: AAA-derived SMC exhibit a distinct morphologic appearance in culture, a diminished proliferative capacity compared to SMC from the adjacent IMA, and a limited in vitro life span. These differences reflect an intrinsic alteration in SMC growth capacity independent of age alone. Tissue-specific processes leading to accelerated replicative senescence may therefore contribute to the selective medial SMC depletion observed in AAAs.

Aged↗
PubMed2000

Selective activation of liver X receptor alpha by 6alpha-hydroxy bile acids and analogs.

We have found that certain natural 6alpha-hydroxylated bile acids are receptor-specific activators of nuclear liver X receptor alpha (LXRalpha) (NR1H3), a nuclear receptor regulating the expression of the cholesterol 7alpha-hydroxylase gene, coding for the rate-limiting enzyme in the major pathway of bile acid synthesis. The LXR homolog, ubiquitous nuclear receptor (UR/LXRbeta) (NR1H2), was also activated by these bile acids, but at higher concentrations than for LXRalpha. Synthetic 6alpha-hydroxylated bile acid analogs were synthesized with LXRalpha-selective agonistic activity, with potential to modulate cholesterol catabolism in hypercholesterolemia.

Bile Acids and Salts↗
PubMed2000

Self-assembled monolayers of rigid thiols.

The preparation, structure, properties and applications of self-assembled monolayers (SAMs) of rigid 4-mercapto-biphenyls are briefly reviewed. The rigid character of the biphenyl moiety results in a molecular dipole moment that affects both the adsorption kinetics on gold surfaces, as well as the equilibrium structure of mixed SAMs. Due to repulsive intermolecular interaction, the Langmuir isotherm model does not fit the adsorption kinetics of these biphenyl thiols, and a new Ising model was developed to fit the kinetics data. The equilibrium structures of SAMs and mixed SAMs depend on the polarity of the solution from which they were assembled. Infrared spectroscopy suggests that biphenyl moieties in SAMs on gold have small tilt angles with respect to the surfaces normal. Wetting studies shows that surfaces of these SAMs are stable for months, thus providing stable model surfaces that can be engineered at the molecular level. Such molecular engineering is important for nucleation and growth studies. The morphology of glycine crystals grown on SAM surfaces depends on the structure of the nucleating glycine layer, which, in turn, depends on the H-bonding of these molecules with the SAM surface. Finally, the adhesion of PDMS cross-linked networks to SAM surfaces depends on the concentration of interfacial H-bonding. This non-linear relationship suggests that the polymeric nature of the elastomer results in a collective H-bonding effect.

Adsorption↗
PubMed2000

Plasminogen activator inhibitor-1 fused with erythropoietin (EPO) mimetic peptide (EMP) enhances the EPO activity of EMP.

Erythropoietin (EPO) mimetic peptide (EMP) encoding sequence was inserted into the gene of plasminogen activator inhibitor-1 (PAI-1) between Ala348 and Pro349 (P2'-P3'), generating a novel gene, PAI-1/EMP (PMP). This was cloned into pET32a expression vector, fused with TrxA peptide in the vector, and a 63-kDa protein was expressed in inclusion bodies with an expression level >50%. The TrxA/PMP protein was purified by Ni-NTA-agarose metal-ligand affinity chromatography to a purity >90%, showing a single, silver-stained band on SDS-PAGE. Using a reticulocyte counting assay, the EPO activity of PMP was determined to be 5,000 IU/mg, 2,500-fold that of EMP.

Amino Acid Sequence↗
PubMed2000

Fatigue in an older population.

OBJECTIVES: Fatigue is a common symptom that has not been studied well in the older populations. The purpose of this pilot study was to examine the epidemiology of fatigue symptoms in relation to demographic and medical characteristics of older patients in a long-term care setting. DESIGN: A cross-sectional interviewer-assisted survey. PARTICIPANTS/SETTING: A total of 199 ambulatory older residents of a single residential care facility. MEASUREMENTS: Along with medical and demographic characteristics, the survey included mental status (Folstein), activities of daily living (Katz and Lawton), depression (Yesavage GDS), a 3-minute walk, a 7-item pain scale, and the modified Piper Fatigue Scale. RESULTS: One-hundred ninety-nine (65%) of 308 potential subjects completed the study (mean age 88 years, 82% female). Of these 199 subjects, 195 (98%) reported some fatigue symptoms (median duration 44 weeks). Significant (P < .0005) relationships were found between fatigue and GDS (r = 0.57), 3-minute walk (r = -0.29), Lawton IADLs (r = 0.31), pain (r = 0.36), and number of medications (r = 0.26). No significant relationships were found between fatigue and age, sex, Folstein score, or number of medical diagnoses. Multivariate regression analysis identified GDS, pain, number of medications and 3-minute walk as significant predictors of fatigue intensity (multiple R = 0.68, r2 = 0.46, P < .02). CONCLUSIONS: Fatigue is a symptom often found among older residents of a residential facility and has important implications for quality of life. Fatigue is poorly recognized and probably undertreated in older people.

Activities of Daily Living↗
PubMed2000

Cholestenoic acid is a naturally occurring ligand for liver X receptor alpha.

Excessive cholesterol is eliminated from extrahepatic cells by reverse cholesterol transport, a process by which neutral sterols are transferred to extracellular acceptor lipoproteins for further transport to the liver. Another process independent of lipoproteins involves excretion of 3beta-hydroxy-5-cholesten-25(R)-26-carboxylic (cholestenoic) acid, a metabolite of 27-hydroxycholesterol. Physiological concentrations of cholestenoic acid activated the nuclear receptor liver X receptor alpha (LXR alpha; NR1H3), but not other oxysterol receptors. As a ligand, cholestenoic acid modulated interaction of LXR alpha with the nuclear receptor coactivator Grip-1. Cholestenoic acid, therefore, may function as a signaling molecule for regulation of lipid metabolism via LXR alpha.

Cell Line↗
PubMed2000

Modulation of endocrine systems and food intake by green tea epigallocatechin gallate.

Green tea polyphenols, especially the catechin, (-)-epigallocatechin gallate (EGCG), have been proposed as a cancer chemopreventative based on a variety of laboratory studies. For clear assessment of the possible physiological effects of green tea consumption, we injected pure green tea catechins ip into rats and studied their acute effects on endocrine systems. We found that EGCG, but not related catechins, significantly reduced food intake; body weight; blood levels of testosterone, estradiol, leptin, insulin, insulin-like growth factor I, LH, glucose, cholesterol, and triglyceride; as well as growth of the prostate, uterus, and ovary. Similar effects were observed in lean and obese male Zucker rats, suggesting that the effect of EGCG was independent of an intact leptin receptor. EGCG may interact specifically with a component of a leptin-independent appetite control pathway. Endocrine changes induced by parenteral administration of EGCG may relate to the observed growth inhibition and regression of human prostate and breast tumors in athymic mice treated with EGCG as well as play a role in the mechanism by which EGCG inhibits cancer initiation and promotion in various animal models of cancer.

Animals↗
PubMed2000

Antidiuretic effects of a factor in brain/corpora cardiaca/corpora allata extract on fluid reabsorption across the cryptonephric complex of Manduca sexta.

Extracts of the brain/corpora cardiaca/corpora allata (Br/CC/CA) complex of Manduca sexta larvae elicit an antidiuretic effect, measured by an increase in fluid reabsorption across the cryptonephric complex of larval M. sexta. Separation of the extract by reversed-phase liquid chromatography gave two fractions with antidiuretic effects. The more potent of these two factors was further characterized for its effects on the cryptonephric complex. Its antidiuretic effect is not inhibited by bumetanide, a drug that inhibits M. sexta diuretic hormone (Mas-DH)-stimulated fluid reabsorption. These data indicate that the mechanism of the antidiuretic effect of the factor is different from that of Mas-DH on the cryptonephric complex. The basal reabsorption of the cryptonephric complex is blocked when treated on the lumen side with bafilomycin A(1), an inhibitor of the H(+)-ATPase, or with amiloride, an inhibitor of the H(+)/K(+) antiporter. However, the antidiuretic-factor-stimulated fluid reabsorption is not affected by either bafilomycin A(1) or amiloride. The increase in reabsorption triggered by the semi-purified factor can be inhibited by Cl(-) channel blockers or by removing Cl(-) from the lumen side of the cryptonephric complex. It appears that this factor activates a Cl(-) pump associated with the cryptonephric complex. Forskolin mimics the effect of this factor on fluid reabsorption, and the effect of forskolin is not inhibited by bumetanide. A selective and potent inhibitor of protein kinase A, H-89, also inhibits antidiuretic-factor-stimulated fluid reabsorption. Addition of the factor to cryptonephric complexes maintained in vitro caused a significant increase in cyclic AMP levels extracted from these tissues compared with values for controls. These data suggest that the antidiuretic effect of the factor in Br/CC/CA extract is mediated by cyclic AMP.

Absorption↗
PubMed2000

[Preliminary study on pathogenicity of hepatitis G virus].

OBJECTIVE: To study the clinical, enzymatic and liver pathological changes in patients with hepatitis G virus (HGV) infection. METHODS: RT- nested PCR was applied to detect HGV RNA in 368 patients with hepatic diseases. The liver biopsy tissue from one liver cirrhosis patient with simple HGV infection was examined. RESULTS: Simple HGV RNA positive were found in 7 cases of 71 acute hepatitis jaundice, in 22 cases of 155 chronic hepatitis and in 3 cases of 51 liver cirrhosis. The immunohistochemistry of the liver biopsy tissue from a liver cirrhosis patient showed HGV NS5 antigen positive. However, HGV infection might occur simply or in combination with hepatitis B or C virus or super infected. CONCLUSIONS: HGV RNA could be detected in acute hepatitis jaundice, chronic hepatitis, hepatitis B or C carriers, liver cirrhosis and hepatocellular carcinoma. HGV is proved to be a hepatotropic virus by pathological examination and immunohistochemistry, the virus located in the cytoplasm of the liver cells. It may cause chronic hepatitis and even liver cirrhosis, so HGV is pathogenic to liver tissue.

Adolescent↗
PubMed2000

Establishment and pathological study of models of chronic obstructive pulmonary disease by SO2 inhalation method.

OBJECTIVE: To establish rat models of chronic obstructive pulmonary disease (COPD) and study the pathological characteristics of airflow obstruction. METHOD: SO2 inhalation method was used to establish rat models. After exposure to SO2 for 7 weeks, peak expiratory flow (PEF), peak inspiratory flow (PIF), intratracheal pressure (IP) and IP slope in rat were measured by Maclab data recording and analysis system. Experimental rats with PEF less than 80% of the mean of the normal rats were classified as airflow obstructed, while those with PEF greater than 80% of mean of normal rats were non-obstructed. Pathological changes in airway and lung tissue were compared between these two groups. RESULT: In experimental animals, PEF was significantly decreased (P < 0.005) and IP slope increased (P < 0.001) as compared with normal rats. Epithelial damage, goblet cell hyperplasia and inflammatory cell infiltration in cartilaginous bronchi were more remarkable in experimental rats with airflow obstruction than those without airflow obstruction (P < 0.001, < 0.01, < 0.001, respectively). Furthermore, pathological changes in airway lumen, epithelium and airway wall in membranous and respiratory bronchioles were more marked in experimental rats with airflow obstruction than those without airflow obstruction (P < 0.001 or P < 0.05). There was a negative correlation between PEF values and epithelial hyperplasia, goblet cell hyperplasia, inflammatory cell infiltration, smooth muscle hyperplasia and mucous plug in membranous and respiratory bronchioles (P < 0.001 or P < 0.05). CONCLUSION: SO2 inhalation may cause chronic bronchitis with airflow obstruction, i.e. COPD in rats. COPD was induced in 64% (16 of 25) of the experimental group rats.

Administration, Inhalation↗
PubMed2000

Molecular and immunohistochemical study of the inactivation of the p16 gene in primary hepatocellular carcinoma.

OBJECTIVE: To determine whether p16 gene is involved in the genesis of primary hepatocellular carcinoma (HCC). METHODS: Twenty-five HCC tumor samples with corresponding non-tumor liver tissue specimens were examined for p16 gene alterations. The identification of deletion of exon 1 and exon 2 in p16 gene was performed using comparative multiplex polymerase chain reaction (PCR) analysis. The point mutation of exon 2 in p16 gene was investigated by single strand conformational polymorphism (SSCP) analysis, and the status of p16 gene methylation was screened using a PCR based methylation analysis. 35 parafin-embedded specimens of HCC with corresponding non-tumor liver tissues, including the 25 cases described above for screening p16 gene alterations, were investigated for p16 protein expression using immunohistochemical analysis. RESULTS: Among 25 cases, 2 homozygous deletions and 1 hemizygous deletion were found in HCC samples. No point mutation was identified in the remaining 22 tumor samples without p16 gene deletions. Hypermethylation was detected in 24% (6/25) of tumor samples. However, the corresponding non-tumor liver tissue specimens were always unmethylated at the p16 locus. Loss of p16 protein expression occurred in 16 of 35 (45.7%) tumor samples, and all the non-tumor liver tissue specimens showed positive p16 staining. For the 25 cases examined for p16 gene alterations, the loss of p16 protein expression was observed in all tumors with p16 gene alterations and also in 3 tumors without p16 gene alterations. CONCLUSION: Inactivation of the p16 gene may play an important role in the genesis of primary hepatocellular carcinoma.

Carcinoma, Hepatocellular↗
PubMed2000

[Clinical observation on treatment of thyrotoxic exophthalmos with jiayanxiao plus tapazole].

OBJECTIVE: To study the therapeutic effect of Jiayanxiao (JYX) on thyrotoxic exophthalmos. METHODS: Forty-three patients were divided randomly into two groups, the 31 Patients in the treated group were treated with JYX plus tapazole, and the 12 patients in the control group were treated with prednisone plus tapazole. The therapeutic course of both groups was 3 months. The symptoms, eye signs, thyroxin level, and other routine laboratory parameters as well as the adverse effect of the therapy were observed and compared between two groups. RESULTS: The total effective rate in the treated group was 80.6%, which was obviously higher than that in the control group (50.0%, P < 0.05). Effect of the treated group in lowering degree of exophthalmos was superior to that of the control group. Effects in elevating vision, decreasing palpebral fissure altitude and lowering serum T3, T4 contents in the two groups were similar (P > 0.05). Moreover, the treated group showed better efficacy in improving clinical symptoms with less adverse effect. CONCLUSION: The therapeutic effect of JYX in treating thyrotoxic exophthalmos is ensured.

Adolescent↗