PubMed Health⌕ Search

Biomedical subjects

X H Lu

Publications and source records attributed to X H Lu.

At least 19 recordsLinked to original sources
PubMed2006

Characterization of an influenza A H5N2 reassortant as a candidate for live-attenuated and inactivated vaccines against highly pathogenic H5N1 viruses with pandemic potential.

We generated a high-growth 7:1 reassortant (Len17/H5) that contained the hemagglutinin (HA) gene from non-pathogenic A/Duck/Potsdam/1402-6/86 (H5N2) virus and other genes from the cold-adapted (ca) attenuated A/Leningrad/134/17/57 (H2H2) strain. Len17/H5 demonstrated an attenuated phenotype in mice and did not infect chickens. Mice administered Len17/H5 either as a live-attenuated intranasal vaccine or as an inactivated intramuscular vaccine were substantially protected from lethal challenge with highly pathogenic A/Hong Kong/483/97 (H5N1) virus and were protected from pulmonary infection with antigenically distinct A/Hong Kong/213/2003 (H5N1) virus. The cross-protective effect correlated with the levels of virus-specific mucosal IgA and/or serum IgG antibodies. Our results suggest a new strategy of using classical genetic reassortment between a high-growth ca H2N2 strain and antigenically related non-pathogenic avian viruses to prepare live-attenuated and inactivated vaccines for influenza pandemic.

Animals↗
PubMed2005

QSAR study on the Ah receptor-binding affinities of polyhalogenated dibenzo-p-dioxins using net atomic-charge descriptors and a radial basis neural network.

A radial basis function neural network (RBFN) has been used to correlate Ah receptor-binding affinities of polychlorinated, polybrominated, and polychlorinated-brominated dibenzo-p-dioxins with molecular weight and eight net atomic charge descriptors. Support vector machine (SVM) and partial least square (PLS) regression models based on the same data set have also been built. Leave-one-out cross-validation was used to train the RBFN, SVM, and PLS models. For predicting Ah receptor-binding affinities, the RBFN model with a squared cross-validation correlation coefficient (q2) of 0.8818 outperforms the SVM and PLS models and also compares favorably with any other reported quantitative structure-activity relationship model based on the same activity data set. The significance of the RBFN model with net atomic charges as descriptors suggests that electrostatic and dispersion-type interactions play important roles in governing the Ah receptor binding of polychlorinated, polybrominated, and polychlorinated-brominated dibenzo-p-dioxins.

Algorithms↗
PubMed2003

Prediction of n-octanol/water partition coefficients for polychlorinated dibenzo-p-dioxins using a general regression neural network.

A general regression neural network was used for the first time to study quantitative structure and property relationships of organic pollutants to correlate and predict n-octanol/water partition coefficients of polychlorinated dibenzo- p -dioxins from their topological molecular descriptors. In total, 42 polychlorinated dibenzo- p -dioxins and dibenzo- p -dioxins were available for this study-42 polychlorinated dibenzo- p -dioxins and dibenzo- p -dioxins in the training data set and 41 polychlorinated dibenzo- p -dioxins in the test data set. Partial least squares regression, back propagation network and general regression neural network models were trained using the training data set, and the accuracy of the models obtained were examined by the use of leave-one-out cross-validation. For prediction of the n-octanol/water partition coefficient, the best method is the general regression neural network. With the test data set, the correlation coefficient, root mean square error and mean absolute relative error for the general regression neural network model are 0.9276, 0.22 and 2.79%, respectively. For describing the structure of polychlorinated dibenzo- p -dioxins, the topological molecular descriptors outperform the mobile order and disorder thermodynamic method.

Algorithms↗
PubMed2003

Pathogenesis of and immunity to a new influenza A (H5N1) virus isolated from duck meat.

The outbreak of avian influenza H5N1 in Hong Kong in 1997 raised concerns about the potential for the H5 subtype to cause a human pandemic. In 2001 a new H5N1 virus, A/Duck Meat/Anyang/AVL-1/2001 (A/Dkmt), was isolated from imported duck meat in Korea. The pathogenesis of this virus was investigated in mice. A/Dkmt virus had low infectivity but was lethal for mice at high doses, and at lethal doses, the virus replicated in the brains of infected mice. A/Dkmt virus cross-reacted poorly with ferret antisera raised against human H5N1 viruses, but prior infection with A/Dkmt virus protected mice from death after secondary infection with human H5N1 virus.

Animals↗
PubMed2001

One-week regimens containing ranitidine bismuth citrate, furazolidone and either amoxicillin or tetracycline effectively eradicate Helicobacter pylori: a multicentre, randomized, double-blind study.

BACKGROUND: The metronidazole resistance of Helicobacter pylori strains has increased rapidly. AIM: To evaluate the efficacy and safety of new 1-week regimens containing ranitidine bismuth citrate, furazolidone and either amoxicillin or tetracycline. METHODS: One hundred and twenty patients with H. pylori-positive inactive duodenal ulcer or non-ulcer dyspepsia diagnosed by endoscopy were recruited randomly to receive one of two regimens for 7 days: ranitidine bismuth citrate, 350 mg b.d., furazolidone, 100 mg b.d., and either amoxicillin, 1000 mg b.d. (n=60), or tetracycline, 500 mg b.d. (n=60). H. pylori infection was identified by rapid urease testing and histology. 13C-Urea breath test was performed to evaluate the cure of H. pylori infection at least 4 weeks after completion of triple therapy. RESULTS: The eradication rates of H. pylori by ranitidine bismuth citrate-furazolidone-amoxicillin and ranitidine bismuth citrate-furazolidone-tetracycline regimens were 82% and 85% (P > 0.05), respectively, by intention-to-treat analysis, and 85% and 91% (P > 0.05), respectively, by per protocol analysis. Adverse effects were mild in both ranitidine bismuth citrate-furazolidone-amoxicillin and ranitidine bismuth citrate-furazolidone-tetracycline groups. CONCLUSIONS: One-week regimens containing ranitidine bismuth citrate, furazolidone and amoxicillin or tetracycline are well tolerated and effective for the eradication of H. pylori.

Adolescent↗
PubMed2000

[Potential anxiolytic role of c-fos antisense oligonucleotide in social-defeated rats].

OBJECTIVES: This study was to explore the therapeutic potential of c-fos antisense phosphorothioate oligonucleotide and the possible molecular mechanism. METHODS: On the basis of the sequence of c-fos mRNA, two 15-mer phosphorothioated oligodeoxynucleotide(ODN) were synthesized. Antisense ODN was corresponded to the initiation codon of c-fos mRNA. The complementary sense and vehicle(saline) served as controls. Anxiety was induced in rats by a social-defeated paradigm and then rats were given a 5-minute exposure to the plus maze and open field test. Rats were injected c-fos antisense, sense ODNs and vehicles into the lateral ventricle through stainless-steel guide cannulate implanted unilaterally from the beginning of the experiment. The expression of the protein product of the immediate early gene c-fos was analyzed with immunochemistry in different brain regions, such as the amygdala and paraventricularis hypothalami nucleus. Computer assisted image analysis was performed to quantify the results of immuno-cytochemistry. RESULTS: Socially defeated c-fos antisense-treated rats displayed obviously reduced anxiety-related behavior, as they spent significantly more time in the open arms of the plus maze compared to sense ODN- and vehicle-treated rats. The behavioral effects were similar to those of established anti-anxiety drugs(diazepam). Antisense oligodeoxynucleotide significantly decreased Fos positive nucleus in paraventricularis hypothalami nucleus. The inhibitory efficiency was 57.03%. CONCLUSION: Our data provide further evidence that c-fos is involved in acute stress elicited anxiety related behavior.

Animals↗
PubMed1998

[The change of soft tissue profile before and after treatment with Begg technique]

OBJECTIVE:This study was to determine the facial soft tissue profile changes Begg technique after treatment. METHODS: 32 patients presented with Angle Class II divide I malocclusion. Lateral cephalograms were taken before treatment and after each treatment stage.Each experimental subject served as its own control by means of cephalometric analysis. RESULTS: Significant soft tissue profile improvement could be expected from first stage to second stage.But third stage of orthodontic treatment had little effective for the profile changes.The soft tissue profile changes which occured during treatment were (1) a retraction of lips and a reduction in the prominence of the lips.(2) an increase of nose prominence. (3) vertical opening at the chin. CONCLUSION: Begg technique was more close to clinical requirement in improvement of soft tissue profile.Achieved a harmony of soft tissue profile must be emphasized as an orthodontic treatment goal during second stage,then establishment of a proper occlusion would be finished.

Journal Article↗
PubMed1997

Structure/function relationship study of Tyr14 and Arg22 in trichosanthin, a ribosome-inactivating protein.

Amino acids Tyr14 and Arg22 in trichosanthin are residues on helix A1 close to the active-site cleft. They are invariant in various type-I and type-II ribosome-inactivating proteins. In this study, Tyr14 was changed to Phe and Arg22 to Lys and Leu. Modified proteins were purified, and activities compared by assaying their median inhibitory concentration (ID50) on a rabbit-reticulocyte-lysate protein-synthesis system. While the ID50 of wild-type trichosanthin was 0.02 nM, those for [Phe14], [Lys22], [Leu22] and [Phe14, Leu22]trichosanthin were 0.10, 0.03, 0.25 and 0.15 nM, respectively. Therefore, compared with Tyr14, Arg22 appears to play a more important role in trichosanthin. Structural studies on [Leu22]trichosanthin showed that two water molecules occupy the space left by the side chain of Arg22, and hydrogen bonds exist between these water molecules and nearby residues to retain the conformation. The use of intermolecular rather than intramolecular hydrogen bonds may have an adverse effect on stability or folding of the protein and results in a mild decrease in activity.

Abortifacient Agents, Nonsteroidal↗
PubMed1997

[The detection of Legionella pneumophila DNA with polymerase chain reaction in water samples].

Legionella pneumophila has been known as an important pathogen causing Legionnaires Disease (LD), responsible for more than 80 per cent of clinical LD cases and majority of the LD outbreaks. In order to detect the existence of Legionella pneumophila strains in water samples, we have developed a ploymerase chain reaction method, using two primers synthesized according to the reported Legionella pneumophila mip gene nucleotide sequence. This method was proved to be highly sensitive (18 cfu/ml) and specific. Two water samples were detected positive. This newly developed method provided a quick, accurate way not only to detect Legionella pneumophila in the diagnosis of LD but also in the capture of suspected pathogen during epidemiologic investgation when LD outbreaks.

Air Conditioning↗
PubMed1994

[Circadian rhythm in susceptibility of mice to the anti-tumor drug carboplatin].

The platinum-containing compounds has become a major chemical agent in the treatment of cancer. A circadian rhythm in the susceptibility of rodents and human being to cisplatin has been demonstrated, the maximal tolerance being found in the animal's active phase. Carboplatin is a second generation analog. Two studies were performed on mice with carboplatin under 12:12 light dark cycle to study its chronotoxicity and chronoeffectiveness. In study I, single intraperitoneal injection of 192mg/kg (LD50) carboplatin was given to four groups of mice at four different circadian stage. It was found that at 50% the overall mortality of mice, there was a mortality difference of 28% for mice receiving the drug at 9 a.m. to 71% for mice receiving drug at 9 p.m. It demonstrated that carboplatin was better tolerated in the animal's early sleep phase. In study II, S180 tumor-bearing mice were treated with 50mg/kg of carboplatin. The longest mean survival time and the lowest marrow toxicity occurred in the group which received the drug at the beginning of the sleep phase. It showed that the susceptibility of mice to carboplatin is circadian stage dependent. These data clearly demonstrate that, by timing the administration of drugs according to body rhythms, such as the host susceptibility-resistance rhythm to a drug, one can gain a therapeutic advantage over an approach which ignores such rhythms.

Animals↗
PubMed1994

[Relation between cesarean section rate and perinatal mortality rate].

In order to evaluate the effect of cesarean section on reduction of perinatal mortality rate (PMR). All cases delivered in Beijing Obstetrics and Gynecology Hospital from Jan. 1, 1980 to Dec. 31, 1992 were analysed. The total number of delivery in study period was 74,199. Number of cesarean section delivery was 18,557. The cesarean section rate was 25.0%. The total number of perinatal baby was 74,914. The number of perinatal death was 1,140. PMR was 15.2%. The 13 years were divided into three periods to compare the cesarean section rate and PMR. The 1st period was from 1980 to 1984. The 2nd period was from 1985 to 1988. Years from 1989 to 1992 were 3rd period. The cesarean section rate was increasing year by year. It was significant since 1985. On the other hand, the PMR was marked decreasing since 1983. But there was no continually decrease in 2nd period. In 3rd period trend of decreasing PMR was shown. There was no significant difference in PMR especially in neonatal mortality rate (NMR) between cesarean section group and vaginal delivery group in 1st period. In 2nd period the PMR and NMR of cesarean section group was higher than that of vaginal delivery group (P < 0.01). In 3rd period it was lower in cesarean section group (P < 0.05). Main causes of neonatal deaths in cesarean section group were congenital abnormalities and respiratory diseases. In 2nd period pulmonary hemorrhage, hyaline membrane disease were marked higher in cesarean section group. It was related to more premature and low birth weight babies in this group.(ABSTRACT TRUNCATED AT 250 WORDS)

Cesarean Section↗
PubMed1993

[Factors influencing the prognosis of gastric cancer patients: a study using international gastric cancer staging classification].

In the 18-year period from 1973 to 1991, 502 cases with gastric cancer were treated surgically at the Peking Union Medical College Hospital. A unified international classification for staging of gastric cancer had been applied to these patients in this study. The pathologic staging classification is based on the extent of the disease at the time of surgical exploration of the abdomen and/or histopathologic study of the excised surgical specimens. According to the new TNM staging classification, the 5-year cumulative survival rates of all surgically treated patients Ia, Ib, II, IIIa, IIIb and IV were 96.25%, 87.34%, 66.11%, 43.70%, 30.33% and 9.36% respectively. It was showed that there is a decreasing tendency in the 5-year survival rates for the depth of invasion of the gastric cancer. The histological types of the gastric cancer had the same prognostic significance as depth of invasion. The 5-year cumulative survival rate of patients with curative surgery was better in the group with chemotherapy (55.6%) than in that without chemotherapy (43%).

Adenocarcinoma↗
PubMed1993

[The common causes and differential diagnosis of malignant jaundice].

To investigate the common causes and differential diagnosis of malignant jaundice, we reviewed 903 cases with obstructive jaundice in PUMC hospital in recent 16 years. 383 of them were malignant jaundice (42.4%). The most common origin of malignant jaundice was carcinoma of the pancreatic head with 198 patients (51.7%), and carcinoma of the ampulla Vater with 94 cases (24.5%) and carcinoma of the extrahepatic bile duct with 71 cases (5.2%). The clinical symptoms and signs were not much helpful to the differentiation of malignant jaundice. No specific early signs were found to the malignant jaundice, but most of the patients felt epigastric distension and distress, anorexia, loss of body weight and fatigue before jaundice appeared. More than one third patients had discontinuous fever. The imaging investigation had decisive roles in the diagnosis and differential diagnosis of the malignant jaundice. The positive rate of diagnosis in sonography was 95.5%, but the correct rate only 85.0% (P < 0.05). We regard that sonography might be the first imaging examination for the malignant jaundice and clue for further investigation. ERCP can clearly reveal the papilla, biliary and pancreatic ducts with high positive rate (97.7%) and correct rate (95.1%). PTC was only used in those patients who had the contraindications to ERCP or the cannulation of ERCP was not successful. The positive rate of PTC was 95.8% in the cases with extrahepatic cholangiocarcinoma. The combination of ERCP and PTC could determine the position and extent of extrahepatic cholangiocarcinoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Evaluation of endoscopic retrograde cholangiopancreatography in diagnosis of chronic pancreatitis].

155 cases of chronic pancreatitis in PUMC hospital from 1952 to 1990 were investigated. Because endoscopic retrograde cholangiopancreatography (ERCP) and exocrine pancreatic function tests have been used since 1974, the diagnostic rate of chronic pancreatitis during 1974-1990 is 6.6 fold as that during 1952-1974. The pancreatic duct in 97 cases among 105 cases with chronic pancreatitis examined by ERCP was compared with CT and ultrasonography in diagnosis of chronic pancreatitis. The accuracy of diagnosis for ERCP is 84.8%, and is significantly higher than that for CT (56.0%, P < 0.01) and ultrasonography (37.8%, P < 0.001). The detective rate of abnormal pancreatic duct for ERCP is 91.4%, and is also significantly higher than that for CT (80.0%) and ultrasonography (79.7%, P < 0.05). These data indicated that the clinical features of chronic pancreatitis in China is more related to biliary diseases, rather than alcoholism. BT-PABA test and ultrasonography are valuable screen examinations, and ERCP is credible important examination in diagnosis of chronic pancreatitis.

Adolescent↗
PubMed1991

Determination of nickel in water by chemiluminescence.

The acetone chemiluminescence determination of nickel in water was investigated. Optimization data for the determination of Ni2+ and interference data for over 20 species are provided. The limit of detection for Ni2+ by this method is 2.5 ng ml-1, and the linear dynamic range is from 10 ng ml-1 to 1 microgram ml-1. The application of the method to the determination of Ni2+ in river and waste waters is discussed.

Luminescence↗
PubMed1991

[Effect of drugs on endoscopic manometry of the sphincter of Oddi].

We used a catheter passing through the papilla duodeni under the view of endoscope, with persistent perfusion system and transducer, to measure the pressure and contraction frequency of sphincter of Oddi (SO) in 10 healthy persons and 20 patients. Meanwhile, we compared the effect of Buscopan, Nitrostat and Vitamin K3 on the pressure and contraction frequency (CF). SO basal pressure (BP) in healthy group was 5.21 +/- 1.61 kPa (mean +/- s), SO peak pressure (PP) 8.21 +/- 1.34 kPa and CF 6.14 waves/min. In the group of peripapillary fistula, SO pressure decreased significantly and CF slowed down greatly. In comparison with the healthy group, SO pressure and CF in the group of gallbladder stone, choledocholithiasis and pancreatic diseases did not show any change of statistic significance. Intravenous injection of Buscopan could decrease SO peak pressure and BP remarkably. Sublingual administration of Nitrostat and intramuscular injection of Vit K3 could reduce SO PP markedly, SO BP didn't change statistically. It was also showed that spheric and semi-spheric papillae had higher pressure than the flat ones (P less than 0.001).

Adult↗
PubMed1990

[Effect of sclerotherapy in patients with bleeding due to portal hypertension].

The author reports the preliminary results of an unrandomized trial comparing the effect of endoscopic variceal sclerosis, shunt surgery and medical therapy in the management of cirrhotic patients with variceal bleeding, sixty-six patients were studied, among them 23 received sclerosis, 25 shunt surgery and 18 medical therapy. Survival was significantly (P less than 0.001) improved in the group with sclerotherapy, with 85% one year survival rate as compared with 45% in the group with shunt surgery and 21% in the group with medical therapy.

Adult↗