Biomedical subjects

D Liu

Publications and source records attributed to D Liu.

At least 271 records · Page 15Linked to original sources

PubMed2000

Importance of phenylalanine 107 in agonist recognition by the 5-hydroxytryptamine(3A) receptor.

The 5-hydroxytryptamine (5-HT)(3) receptor is a member of the ligand-gated ion channel receptor family with significant homology to the nicotinic acetylcholine, gamma-aminobutyric acid(A), and glycine receptors. In this receptor class, the agonist binding site is formed by parts of the extracellular amino-terminal region. This study examines the effects of altering phenylalanine 107 (F107) of the 5-HT(3AL) subunit, obtained from NG108-15 cells, using site-directed mutagenesis. The wild-type (WT) and mutant receptors were expressed in HEK 293 cells and characterized using both whole-cell patch-clamp and radioligand binding. The tyrosine mutant F107Y exhibits a significantly lower affinity for the agonist 5-HT (K(i) = 203 versus 15.6 nM) and an increase of similar magnitude in the EC(50) value (10.6 versus 1.2 microM) compared with WT. The activation kinetics of the maximal currents generated by 5-HT with this mutant were markedly slower than those of the WT receptor, but application of supramaximal concentrations of the agonist markedly decreased the time to half-peak. The asparagine mutant F107N displayed a significantly higher affinity for 5-HT than the WT receptor (1.62 versus 15.6 nM), which was mirrored in direction and magnitude by changes in the EC(50) value for this agonist (0.2 versus 1.2 microM). In contrast to the WT receptor, the mutant F107N was activated by acetylcholine (EC(50) = 260 microM). The response to acetylcholine was blocked by the 5-HT(3) receptor antagonist renzapride with a similar IC(50) value as that determined against currents generated by 5-HT in the WT receptor. These data suggest that F107 is an important determinant of agonist recognition at the 5-HT(3) receptor.

Animals↗

PubMed2000

[Estrogen receptor gene polymorphism and its association with clinicopathological manifestation of lupus nephritis].

OBJECTIVE: To investigate the distribution of estrogen receptor (ER) in patients with lupus nephritis (LN), and the association between ER gene polymorphism and the clinical and pathological features of the disease. METHODS: The Pvu II and Xba I restriction fragment length polymorphism (RFLP) of estrogen receptor gene were analyzed in 245 biopsy proven LN patients (58 males and 187 females) and 172 normal controls(101 males and 71 females) by PCR-RFLP. The clinical and pathological features of 49 male and 152 female LN patients with genotype PpXx or Ppxx, ppxx were then analyzed respectively. RESULTS: It was found that genotype PpXx and ppxx, Ppxx were three major genotypes of ER gene in both lupus patients group and control group. The distribution of ER gene polymorphism was quite different in lupus patients of different genders. The frequency of the PpXx genotype was significantly higher in male LN patients than in both the gender matched normal controls (P<0.05) and the female LN patients (P<0.05), while no difference was shown in the frequency of PpXx genotype between female LN patients and female controls. Interestingly, varied clinical and renal pathological features were also demonstrated in female patients with different genotypes of ER gene. CONCLUSION: The distribution of ER gene polymorphism in LN patients varies with gender. The PpXx genotype of ER gene may be associated with the susceptibility of LN in male. ER gene polymorphism is probably one of the genetic factors contributing to the development of clinical heterogeneity and sexually dimorphic manifestations of LN.

Adolescent↗

PubMed2000

[Polymorphism of human alleles associated with genetic resistance against HIV-1 infection and its implications].

To investigate the genetic susceptibility of different ethnic populations to human immunodeficiency virus-1(HIV-1) infection by comparing the characteristics of gene mutation frequency and polymorphism of CCR5, CCR2 and SDF-1 alleles among different nationalities in the world. The recently reported data on AIDS progression in patients, and on gene mutation and polymorphism of CCR5, CCR2b and SDF-1 genes were collected. The data also included the HIV-1-associated genes polymorphisms of the Chinese individuals detected by the present authors. There was a significant link between the gene mutation, polymorphism of HIV-1-associated genes, genetic susceptibilities and the AIDS progression in patients, although the differences of HIV-1-associated gene mutation, polymorphisms existed among different ethnic populations in the world. The Chinese individuals are more likely to be infected by the M-tropic HIV-1 strain than the American Caucasian. The Chinese individuals have very low gene mutation of CCR5Delta32, which would be helpful for the prevention and gene therapy against the HIV-1 infection.

Acquired Immunodeficiency Syndrome↗

PubMed2000

N-(4-hydroxyphenyl)retinamide in the chemoprevention of squamous metaplasia and dysplasia of the bronchial epithelium.

Lung cancer remains the number one cause of cancer-related deaths in the United States. To reduce the mortality associated with this disease, individuals at risk must be identified prior to the development of lung cancer, and effective prevention strategies must be developed. One such strategy is to use retinoids like N-(4-hydroxyphenyl)retinamide (4-HPR), which has been found to possess chemopreventive activities in preclinical studies. In this study, 139 smokers were registered and 82 were randomized onto a double-blinded, placebo-controlled chemoprevention trial of 4-HPR administered p.o. (200 mg once daily). Of these, 70 participants were eligible for response evaluation. Biopsies were obtained at six predetermined sites in the bronchial tree from participants before and at the completion of 6 months of treatment. 4-HPR treatment had no measurable effect on histopathology (squamous metaplasia and dysplasia) in the bronchial epithelium of current smokers. 4-HPR was detected (104.5+/-64.0 ng/ml, mean +/- SD) in the serum of participants, supporting its potential bioavailability. Serum retinol levels decreased markedly (44% of placebo-treated patients) as a consequence of 4-HPR treatment. Notably, the mRNA level of retinoic acid receptor beta, which is typically increased by retinoid treatment, did not change in the bronchial epithelium of 4-HPR-treated participants. Clonal populations of bronchial epithelial cells were detected by analysis of loss of heterozygosity at putative tumor suppressor loci on chromosomes 3p, 9p, and 17p, and these changes were not altered by 4-HPR treatment. In conclusion, at this dose and schedule, 4-HPR was not effective in reversing squamous metaplasia, dysplasia, or genetic and phenotypic abnormalities in the bronchial epithelium of smokers.

Adult↗

PubMed2000

Molecular cloning and characterization of the promoter region of the inducible nitric oxide synthase gene of the rat.

To investigate the mechanism by which inducible nitric oxide synthase (iNOS) within vascular smooth muscle cells (VSMC) is expressed following exposure to proinflammatory cytokines, we cloned the promoter region of the rat iNOS gene by a single specific primer PCR cloning strategy. The 5;-flanking region of the rat iNOS gene contains interferon-gamma (IFN-gamma)- and tumor necrosis factor-alpha (TNF-alpha)-responsive elements and an NF-kappaB-binding consensus sequences. The position and alignment of these consensus sequences are distinct from those in the mouse iNOS and human iNOS genes. It was shown that some nuclear factor(s) which bound specifically to the fragment of the rat iNOS gene containing several consensus sequences were produced after VSMC were treated with interleukin 1 (IL-1) and IFN-gamma.

Animals↗

PubMed2000

Differential roles of corticotropin-releasing factor receptor subtypes 1 and 2 in opiate withdrawal and in relapse to opiate dependence.

The possible effects on the morphine withdrawal signs of the nonspecific corticotropin-releasing factor (CRF) receptor antagonist alpha-helical CRF, the selective CRF receptor subtype 1 antagonist CP-154,526 and the selective CRF receptor subtype 2 antagonist antisauvagine-30 (AS-30) were investigated in rats. The most withdrawal signs, including jumping, teeth chatter, writhing, shakes, lacrimation, piloerection, irritability and diarrhoea, were attenuated by pretreatment with alpha-helical CRF (10 microg i.c.v.) and CP-154,526 (30 mg/kg i.p.). However, no morphine withdrawal signs except for diarrhea were significantly affected by pretreatment with AS-30 (10 microg, i.c.v.). To investigate the possible role of different CRFR antagonists (alpha-helical CRF, CP-154,526 and AS-30) in relapse to opiate dependence, the 28-day extinction of morphine-conditioned place preference (CPP) was used. The morphine-CPP disappeared following a 28-day extinction and then was reactivated by a single injection of 10 mg/kg morphine. Pretreatment with alpha-helical CRF (10 microg, i.c.v.) and CP-154, 526 (30 mg/kg, i.p.) could significantly block this reactivation of morphine-CPP. In contrast, pretreatment with AS-30 (1 or 10 microg i. c.v.) did not affect this reactivation of morphine-CPP. The present study demonstrated that activation of the CRF receptor is involved in morphine withdrawal signs and relapse to morphine dependence, and that the role of CRF receptor subtypes 1 and 2 in withdrawal and reactivation of morphine dependence is not identical. CRF receptor subtype 1, but not subtype 2, is largely responsible for the action of the CRF system on opiate dependence. These results suggest that the CRF receptor antagonists, particularly the CRF receptor subtype 1 antagonist, might be of some value in the treatment and prevention of drug dependence.

Animals↗

PubMed2000

Clinical study of embolization of arteriovenous malformation in the oral and maxillofacial region.

OBJECTIVE: To evaluate the value of embolization on arteriovenous malformations (AVM) in the oral and maxillofacial region and to investigate the efficacy of several different embolic materials. CLINICAL MATERIALS AND METHODS: 10 cases with AVMs, including 5 AVMs mainly in the soft tissue and 5 intraosseous lesions, were embolized. Clinical and angiographic effects were analyzed during the 3 to 16 months follow-up. RESULTS: In the 5 cases embolized without other treatment, 1 case was embolized 3 times, 3 cases twice, and 1 case once. In these cases, postembolization angiograms revealed complete or nearly complete disappearance of the lesions. In the other 5 cases, embolized before surgery, intraoperative bleeding was significantly decreased. All these patients were free of recurrence during follow-up. Among the materials employed, NBCA seemed to offer a better result. CONCLUSIONS: Embolization may serve as the primary therapy for some AVMs in the oral and maxillofacial region, or as a routine preoperative adjunct for patients with severe intraosseous or disfiguring AVMs.

Adolescent↗

PubMed2000

Mechanism of free radicals on the molecular fluidity and chemical structure of the red cell membrane damage.

This paper investigated the mechanism for the rheological dysfunction of red blood cell (RBC) caused by free radicals. Normal RBCs were collected from healthy volunteers. Fenton system was added to the RBCs and allowed to react for 30 minutes in vitro. The RBC membrane molecules were damaged due to the free radicals reaction. It was found that: (1) The protein configurations changed such as the ratio decreasing in alpha-helix and increasing in both of beta-sheet and coiled-coil; (2) -P=O/-P-O chemical group ratio in phospholipids increases; (3) the molecular rotational correlation times of proteins and lipids were extremely elevated; (4) the membrane shear elastic modulus was significantly enhanced. The present results support that the chemical structure changes led by free radicals are ultimately responsible for the reduction in molecular fluidity of RBC membrane.

Elasticity↗

PubMed2000

[Study of relativity between HBV M and HBV DNA in the cases with hepatitis B].

OBJECTIVE: Serum samples of 414 cases with hepatitis B were detected for hepatitis B markers (HBV M) and HBV DNA, in order to investigation the relationship between HBV M and HBV DNA, and its clinical significant. METHODS: HBV M and HBV DNA were detected by ELISA and blot hybridization methods respectively. RESULTS: HBV DNA positive rates in the groups of acute and chronic hepatitis B were higher than that in the group of liver cirrhosis (P <0.01); HBV DNA positive rates had no apparent difference between the HBsAg, HBeAg, anti-HBc positive group and the HBsAg, anti-HBs, anti-HBc positive group. Direct relativity was shown between the titer of HBsAg and/or HBeAg and the positive rate of HBV DNA. CONCLUSIONS: HBV DNA can be treated as a sign of HBV activity; the appearance of anti-HBs can not be taken as indicator of ceasing of HBV replication; the changes in HBsAg and HBeAg titers may be used as clinical evaluation on HBV replication and index for anti-viral therapeutic effect.

Adult↗

PubMed2000

[Study on the correlation of clinical features, pathology and immunohistochemistry of single HGV infection].

OBJECTIVE: Our objective is to study the pathogenicity of the single HGV infection. METHODS: The ELISA was used to check the serum anti-HGV antibody of 36 cases. Immunohistochemistry staining of hepatic tissue was conducted by using HGV NS5 McAb in 20 single HGV infected patients who were further confirmed by clinical diagnosis and pathological evidence. These patients included 10 cases of acute hepatitis, 7 cases of chronic hepatitis, 1 cases of subacute severe hepatitis and 2 cases of chronic severe hepatitis. RESULTS: (1) Clinical manifestation: Acute hepatitis occurred abruptly, accompanied with fever, inertia, nausea and sometimes with vomiting and oil disgust. Chronic hepatitis developed slowly and presented mild symptoms. Severe hepatitis presented an acute onset, extreme fatigue, serious gastrointestinal symptoms, or even hepatic coma developed. (2) Changes of ALT and AST: ALT and AST increased slightly in chronic hepatitis and moderately in acute and severe hepatitis. The disproportion between ALT and BiL sometimes occurred in severe hepatitis. (3) Pathological changes in hepatic tissue: Acute hepatitis was characterized by hepatocyte swelling and inflammatory cells infiltrated in portal duct areas. Chronic hepatitis was identified by hepatocyte swelling, piecemeal necrosis or spotty necrosis, slight infiltration of inflammatory cell in portal duct areas and fibrosis. Severe hepatitis appeared as hepatic cell necrosis, inflammatory cell infiltration and slight fibrosis. CONCLUSIONS: Infection of HGV can give rise to acute hepatitis, chronic hepatitis and severe hepatitis.

Adult↗

PubMed2000

[Academic achievements of Chen Xiuyuan's records of popular medicine (Yi xue cong zhong lu].

Yi xue cong zhong lu (by Dr. Chen Xiuyuan, Qing dynasty) is one of the medical records mainly on the treatment of internal diseases. The contents are rich with a careful differentiation of pulses and syndromes, and a thorough investigation of pathogenesis. The Chen's exposition was based on the gists of various Traditional Chinese Medicine classics, achieved mastery through a comprehensive study of the classics and found out the abnormality from normality. The treatment was elaborated with the collection of the essence of predecessors' merits and folk experiences, such as the treatment for dysentery, obstructed urination, sputum syndrome, cough and diarrhea, etc. It gives expression to Chen's merits of syndrome differentiation and prescription selection.

China↗

PubMed2000

Effect of selenium on human myocardial glutathione peroxidase gene expression.

OBJECTIVE: To examine the role of selenium (Se) in the expression and activity of selenium-dependent cellular glutathione peroxidase (GPX-1). METHODS: 46 patients with atrial septal defect or ventricular septal defect were separated into two groups, a control group (23 cases) and a Se supplementation group (23 cases). The Se supplementation group received 400 micrograms selenium per day for 7 days before surgery. We used biochemical techniques, atomic absorption, RT-PCR and cDNA sequence testing methods to evaluate and compare the changes during ischemia/reperfussion (I/R) in myocardial melondialdehyde (MDA) level, GPX activity and gene expression level, GPX cDNA nucleotide sequence, selenium and calcium and magnesium concentration. RESULTS: Before ischemia, taking selenium for 7 days did not change the selenium concentration in either plasma or blood cells in either group. The GPX mean activity level in the selenium group was slightly lower than that in the control group, and the MDA level was equal in both. After 30 minutes of reperfusion, the Se level in plasma and blood cells remained constant, while the myocardial Se concentration and GPX gene expression in the Se group increased significantly. The MDA level in the Se group reduced 4.2%, compared to an 8.2% rise in the control group. The mean level of GPX activity in the Se group was slightly lower than that in the control group. Both pre- and post-myocardial reperfusion, the Se group had a higher rate of myocardial GPX gene expression, and the nucleotide sequence was normal. These results indicate that supplementing Se is not likely to enhance myocardial GPX activity, but it could increase the GPX gene expression level, and thereby enhance the Se patients' myocardial antioxidant level during I/R, allowing free radicals to be scavenged as soon as they are generated. CONCLUSION: Se supplementation could increase myocardial selenium content and improve GPX gene expression during I/R, and in this way defend against free radical peroxide damage to the myocardium.

Adolescent↗

PubMed2000

[Expression of transforming growth factor-beta 1 mRNA and osteopontin mRNA in UMR-106 cells under mechanical stimulation].

OBJECTIVE: To investigate the effects of the mechanical stretching on the expression of osteopontin (OPN) mRNA and transforming growth factor-beta 1 (TGF beta 1) mRNA in a rat osteosarcoma cell line (UMR-106), and to unveil the cellular mechanism of mechanical force-induced bone remodeling. METHODS: An apparatus was designed and fabricated by which force was loaded onto the cultured cells in vitro. Digoxin-labeled cDNA probes were used for in situ hybridization in combination with image analysis technique to relatively quantify the intensities of the hybridization signals. RESULTS: Various magnitudes and durations of the mechanical stretching did exert different influences on the intensities of the mRNAs' expression. Of all the combinations, the low tension/frequency group showed the most remarkable alteration of TGF-beta 1, as increased from 0.0899 to 0.1756 (P < 0.01). Some putative relations lay between the expressions of the OPN mRNA and the TGF-beta 1 mRNA. CONCLUSION: The mechanical stretching can inevitably influence the expression of OPN mRNA and TGF-beta 1 mRNA. The beneficial alteration obtained in using low tension/frequency action mode suggests and verifies the use of relatively constant and light force to move teeth in clinical orthodontics.

Animals↗

PubMed2000

Right ventricular function of patients with septic shock: clinical significance.

OBJECTIVE: To understand the effect of right ventricular dysfunction on circulatory supportive therapy in patients with septic shock. METHODS: 25 patients with septic shock who were admitted consecutively to the intensive care unit (ICU) of Peking Union Medical College Hospital were observed prospectively. Hemodynamic profile of the left side and right side heart was monitored with right ventricular ejection fraction catheter and transthoracic echocardiography. Intramucosal pH (pHi) and oxygen delivery were also monitored to illustrate any relation with patient outcome. RESULTS: Stroke volume index (SVI) and right ventricular ejection fraction (RVEF) were significantly higher in survivors than in nonsurvivors (P < 0.01 and < 0.05, respectively). The pulmonary vascular resistance index (PVRI) was significantly lower in survivors (P < 0.01). At the onset of shock, the left ventricular end-diastolic volume index (LVEDVI) of both groups was very low, and steadily increased in survivors but not in nonsurvivors. Left ventricular ejection fraction (LVEF) and systemic vascular resistance index (SVRI) decreased during treatment, which were not different in both groups. Right ventricular end-diastolic volume index (RVEDVI) increased in both survivors and nonsurvivors. Oxygen delivery of nonsurvivors was significantly lower than that of survivors. LVEDVI and RVEF were correlated with SVI in both survivors and nonsurvivors. CONCLUSIONS: The impairment of right heart function may be more severe than that of left heart function in the patients with early septic shock. "Right heart priority" must be seriously considered in supportive treatment of patients with septic shock. The present treatment of septic shock has significant limitations, and even aggravates the existing cardiac dysfunction.

Adult↗

PubMed2000

[Clinical results of transmyocardial laser revascularization for 77 patients with coronary artery disease].

OBJECTIVE: To analyses the clinical results of transmyocardial laser revascularization (TMLR) for 77 patients with coronary artery diseases (CAD). METHODS: The mean age of the patients was (65 +/- 7) years. Previous medical record included CABG (6 patients), PTCA (9), AMI (66.2%), hypertension (70.1%), and diabetes mellitus (45.5%). TMLR was performed on the beating heart via a left anterolateral thoracotomy at the fifth intercostal space. Transesophageal echocardiography showed transmyocardial penetration of 23 +/- 6 channels. RESULTS: The hospital mortality was 3.8%, and postoperative complications were AMI (3.8%), left ventricular failure (2.6%), PVC (5.2%). After operation, the mean CCS angina class was improved from the baseline 3.5 +/- 0.7 to 2.1 +/- 0.3 at 3 months, 1.7 +/- 0.3 at 6 months, 1.7 +/- 0.3 at 12 months and 1.8 +/- 0.4 at 24 months. One patient died of AMI and two died not due to cardiac events during a follow-up of 3 to approximately 24 months. Echocardiography showed that the average of left ventricular ejection fractions was improved significantly at 6 months after operation compared with the preoperative value (P = 0.0457). (201)TI-SPECT showed a remarkable improvement in reversible ischemia in 70% patients followed up. Metabolic stress test for 20 patients followed up patients demonstrated an average increase in exercise tolerance from 7.1 +/- 3.2 min at the baseline to 9.6 +/- 1.3 min at 12 months (P = 0.021). Similarly the METs increased from 4.3 +/- 2.1 at the baseline to 5.4 +/- 2.0 at 12 months. CONCLUSIONS: TMLR is a safe and effective procedure for the treatment of end stage coronary artery diseases not amenable to PTCA or CABG. The effect of TMLR is associated with indication, correct evaluation of myocardial ischemia, and management for postoperative complications.

Aged↗

PubMed2000

[Diagnosis and treatment of pheochromocytoma].

OBJECTIVE: To improve the diagnosis and treatment of pheochromocytoma. METHODS: From 1958 to 1998, 286 cases of pheochromocytoma, confirmed by open surgery and pathology, were retrospectively analyzed. RESULTS: The tumors in the adrenal gland were seen in 220 cases, and in the external adrenal gland in 66. Of 29 cases of malignant pheochromocytomas, 7 were noted in the adrenal and 22 in the external adrenal gland. 19 cases showed stationary pheochromocytomas without clinical features. Total resections were performed in 281 cases. CONCLUSION: The operative mortality could be reduced by the prevention of potential myocardiopathy. The diagnosis of malignant pheochromocytoma should depend upon the long-term follow up.

Adolescent↗

PubMed2000

[Establishment and initial utilization of an arithmetic model of chronic hepatic diseases].

OBJECTIVE: An arithmetic model was established to reflect the natural development of chronic hepatitis B, and to help decision making in public health. METHODS: The frame of this model was composed of 6 states - chronic hepatitis B (CHB), natural recovery (NR), compensated cirrhosis (CIR), decompensated cirrhosis (DEC), hepatocellular carcinoma (HCC) and death (DEA). It was supposed that each state would develop into the other possible states at different rates after different years. According to many related reports, 15 values or functions of transfer rates were calculated, and on the ground of them the present model - the Foxpro program was established. Hypothetical CHB and other patients had been introduced to simulate the natural course over 55 years. RESULTS: It was shown that the observation period when 50% of NR, CIR, DEC and HCC were developed from CHB were 3, 11, 20 and 24 years respectively. The CHB, CIR, DEC and HCC patients could last 30, 12, 4 and less than 1 year respectively before half of them died. At the 30(th) year, proportions of death were 41.3% from HCC, 33.0% from DEC and 25.7% from the other causes. CONCLUSION: After the comparison between the main results of the model and real reports from the past years, it could be concluded that the model was reliable.

Hepatitis B, Chronic↗

PubMed2000

[Analysis of clinical characteristic and tendency on inpatients with colorectal cancer in Shanxi Tumor hospital from 1989 - 1999].

OBJECTIVE: To understand the clinical characteristics and variable tendency on inpatients with colorectal cancer admitted to Shanxi Tumor Hospital from 1989 - 1999. METHODS: Statistical analysis on all cases from 1989 - 1999. RESULTS: Results showed that 3,050 cases with colorectal cancer were admitted during 11 years including 2,246 (73.64%) cases of surgical patients. The 1,168 cases males and 1,078 females were with ratio being 1.08/1.0 (M:F). There was no obvious change on the numbers of inpatient from 1991 to 1994, but the numbers was higher than that in 1989 and 1990. The numbers of inpatient rose from 1995 to 1999 year by year. In all the admitted inpatients during the 11 years, 1,348 cases were from countryside and 898 cases from city with the ratio being 1.5/1.0. When adjusted by the general population in 1992, the frequency of the admitted patients was higher in city (14.66/10(5)) than that in countryside (5.96/10(5)). Regarding the distribution of inpatients, it was found higher in Tiayuan city and Jinzhong area than that in else areas. The age of inpatients rose from 40 years and reached high peak in 51 - 70 years. Dukes stages showed that most of inpatients were middle or advanced stage and chief ill location was in rectal (82.36%). Most histological classification referred to adenocarcinoma (56.23%) and papilla adenocarcinoma (20.88%). CONCLUSION: Data suggested that it is very important to strenghen the knowledge of prevention and self-protection of colorectal cancer. Screening and early diagnosis and early treatment should be paid great attention to improve survival rate among high risk population.

ABO Blood-Group System↗