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L Y Li

Publications and source records attributed to L Y Li.

At least 91 records · Page 5Linked to original sources
PubMed1994

Sequencing for 4 single-copy DNA segments from human chromosome 8q24.1.

A successful method for constructing human chromosome 8q24.1 band specific probe pool by microdissection and microcloning is described in this paper. The probe pool was proved to be band-specific by fluorescence in situ hybridization. Through Southern blot analysis, 34 single copy DNA segments were obtained and four of them were sequenced. It is possible to provide useful landmarks for constructing human chromosome 8q24.1 physical map and STSs map.

Base Sequence↗
PubMed1993

Tetracycline regulation of genes on Bacteroides conjugative transposons.

Human colonic Bacteroides species harbor a family of large conjugative transposons, called tetracycline resistance (Tcr) elements. Activities of these elements are enhanced by pregrowth of bacteria in medium containing tetracycline, indicating that at least some Tcr element genes are regulated by tetracycline. Previously, we identified a central regulatory locus on the Tcr elements that contained two genes, rteA and rteB, which appeared to encode a two-component regulatory system (A. M. Stevens, J. M. Sanders, N. B. Shoemaker, and A. A. Salyers, J. Bacteriol. 174:2935-2942, 1992). In the present study, we describe a gene which is located downstream of rteB in a separate transcriptional unit and which requires RteB for expression. Sequence analysis of this gene showed that it encoded a 217-amino-acid protein, which had no significant sequence similarity to any proteins in the GenBank or EMBL data base. An insertional disruption in the gene abolished self-transfer of the Tcr element to Bacteroides recipients, indicating that the gene was essential for self-transfer. The disruption also affected mobilization of coresident plasmids. Mobilization frequency was reduced 100- to 1,000-fold if the recipient was Escherichia coli but was not affected to the same extent if the recipient was an isogenic Bacteroides strain. The complex phenotype of the disruption mutant suggested that the newly identified gene, like rteA and rteB, had a regulatory function. Accordingly, it has been designated rteC. Our results indicate that regulation of Tc(r) element functions is unexpectedly complex and may involve a cascade of regulators, with RteA and RteB exerting central control over secondary regulators like RteC, which in turn control subsets of Tcr element structural genes.

Bacteroides↗
PubMed1993

Characterization of the mobilization region of a Bacteroides insertion element (NBU1) that is excised and transferred by Bacteroides conjugative transposons.

Many Bacteroides clinical isolates carry large conjugative transposons that, in addition to transferring themselves, excise, circularize, and transfer smaller, unlinked chromosomal DNA segments called NBUs (nonreplicating Bacteroides units). We report the localization and DNA sequence of a region of one of the NBUs, NBU1, that was necessary and sufficient for mobilization by Bacteroides conjugative transposons and by IncP plasmids. The fact that the mobilization region was internal to NBU1 indicates that the circular form of NBU1 is the form that is mobilized. The NBU1 mobilization region contained a single large (1.4-kbp) open reading frame (ORF1), which was designated mob. The oriT was located within a 220-bp region upstream of mob. The deduced amino acid sequence of the mob product had no significant similarity to those of mobilization proteins of well-characterized Escherichia coli group plasmids such as RK2 or of either of the two mobilization proteins of Bacteroides plasmid pBFTM10. There was, however, a high level of similarity between the deduced amino acid sequence of the mob product and that of the product of a Bacteroides vulgatus cryptic open reading frame closely linked to a cefoxitin resistance gene (cfxA).

Amino Acid Sequence↗
PubMed1993

[Effects of Ilexonin A on chemical salpingitis induced tubal obstruction in rats].

Ilexonin A, a new drug in improving the blood circulation and microcirculation, is extracted from Ilicis pubescentis. The preventive and therapeutic effects of Ilexonin A on chemical salpingitis induced tubal obstruction (CSTO) with morphological and hemorheological change in rats was studied. Results showed that Ilexonin A was effective in treating (CSTO by oppositing the degeneration and necrosis of epithelium, inhibiting the hyperplasia of connective tissue, and reducing the infiltration of inflammatory cells. The improvement of morphology was more significant in treated groups than that in controls (P < 0.05-0.01). The indices concerning model rat's hemorheology were also analysed between treated groups and controls. It indicated that Ilexonin A could improve the viscosity of blood and aggregation of red blood cells. It is suggested Ilexonin A could promote the absorption of inflammatory substances as a result of improving hemorheology.

Animals↗
PubMed1993

[Pulmonary embolism: an analysis of 25 patients].

We reported 25 cases of patients with pulmonary embolism (PE) definitely diagnosed in our hospital from 1983 to 1990. Twenty-one cases of them were found in the last 5 years. This indicated that the discovery rate had increased obviously. Five of these patients were confirmed by autopsy, the other twenty cases were diagnosed by clinical manifestations combined with perfusion-inspiration lung scans and chest roentgenogram. Due to the prompt diagnosis and the appropriate use of anticoagulants, 72% of the patients survived after treatment. We suggest that all the patients with suspected PE should take perfusion-inspiration lung scans, because this is a noninvasive and reliable method. Digital subtraction angiography is necessary for some patients. Routine chest radiography, arterial blood gas analysis, intrapulmonary shunt test, deep venography or nuclide scan of lower extremities are also useful methods for the diagnosis of PE.

Angiography, Digital Subtraction↗
PubMed1992

Purification of opioid receptor in the presence of sodium ions.

Opioid receptor was solubilized from rat brain membranes with a mixture of the detergents CHAPS and digitonin in the presence of protease inhibitors and 1 M NaCl. The solubilized receptor bound mu-opioid agonists and antagonists with affinities similar to those of native membrane receptor. The affinity of solubilized receptor for the agonist PL017 was greatly reduced by GTP gamma S, suggesting the receptor is still associated with G-protein. The solubilized material was passed through an opioid antagonist (10cd) affinity column and a wheat germ agglutinin column, set up in series, to obtain a partially purified receptor preparation. This partially purified material bound mu-agonist with low affinity and the binding affinity was no longer affected by GTP gamma S. The partially purified receptor was further purified by repeating the affinity and lectin chromatography with smaller size column. Binding of opioid antagonist [3H]diprenorphine to the partially or purified receptors was dependent upon the presence of sodium ions. The purified receptor showed saturable and stereospecific binding for opioid ligands, was predominantly of the mu-type, and exhibited as a diffuse band with a medium molecular mass of 62 kD upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The average specific binding activity of the purified receptor was 18.8 +/- 2.3 pmol/micrograms protein, a value close to the theoretical estimation.

Animals↗
PubMed1992

[Pulmonary angitis and granulomatosis].

16 patients of Wegener's granulomatosis, 4 of allergic angiitis and granulomatosis, 3 of lymphomatoid granulomatosis and 1 of necrotizing sarcoid granulomatosis were reported. In this group of different diseases, characteristic pathological manifestations are inflammatory cellular infiltration of vessel wall combined with destruction and necrosis of pulmonary parenchyma. There was little difference in their clinical features. In most of the cases, fever and systemic symptoms related to lung and extrapulmonary organs were present. Correct diagnosis of these diseases is very important, because both the prognosis and therapy are different. As for the prognosis, it ranges from benign (necrotizing sarcoidal granulomatosis) to very malignant (lymphomatoid granulomatosis). The clinical features of each illness were reviewed with emphasis on their histopathologic findings. The therapeutic effect and final outcome were followed.

Adolescent↗
PubMed1992

[The treatment of small cell lung cancer].

Forty-nine cases with small cell lung cancer (SCLC) treated with chemotherapy and radiotherapy were analyzed. Eight of them were of limited disease (LD), and 41(83.7%) had extensive disease (ED). Forty six were treated on a protocol comprising the induction with cyclophosphamide 1g i.v. on days 1st and 8th, vincristine 1-2mg, i.v. on days 1st and 8th, etoposide 100mg i.v. on days 3rd-7th and methotrexate 20mg i.v. on day 3rd, 5th, 9th, 11th and than repeated with the second course of treatment after 21 days. Eight patients (17.4%) responded completely. There were 29 cases with partial response (63%). The total response rate was therefore 80.4%. Then radiotherapy (50 GY Over 4 weeks) was administered to primary cancer area in 36 patients of good response. The CR was increased from 19.4% to 55.6%. Twenty patients had CR. These patients were treated by late intensification with average of six cycles. The median survival period was 10 months. 21 patients (58.3%) were alive more than 1yr. 10 patients (27.8%) survived more than 2 yrs. Six patients (24%) were alive more than 3 yrs. One patient survived over 7 yrs. It was suggested that combined therapy is important for achieving a better response. CR is beneficial for long term remission. Late intensification is a kind of treatment with minimal toxicity and longer remission. Metastases to the central nervous system usually caused death, so prophylactic CNS irradiation (PCI) should be used in patients with ED for achieving a longer remission.

Adult↗
PubMed1991

Codon usage, transfer RNA availability and mistranslation in amino acid starved bacteria.

The fidelity of codon reading was examined in amino acid starved Escherichia coli. In one case the level of misincorporation of methionine was measured at an isoleucine residue encoded by either the commonly used AUU codon or the rarely used AUA codon. In this situation we found the frequency of methionine misincorporation to be very low and to be unaffected by the identity of the isoleucine codon. In other experiments histidine misincorporation for glutamine was measured in glutamine starved cells with normal levels of histidine-specific tRNA and cells overproducing this tRNA. Cells overproducing the tRNA had higher levels of misincorporation.

Amino Acid Sequence↗
PubMed1991

Impact on catalysis of secondary structural manipulation of the alpha C-helix of Escherichia coli dihydrofolate reductase.

The alpha C-helix of Escherichia coli dihydrofolate reductase has been converted to its counterpart in Lactobacillus casei by a triple mutation in the helix (H45R, W47Y, and I50F). These changes result in a 2-fold increase in the steady-state reaction rate (kcat = 26 s-1) that is limited by an increased off rate for the release of tetrahydrofolate (koff = 40 s-1 versus 12 s-1). On the other hand the mutant protein exhibits a 10-fold increase in the KM value (6.8 microM) for dihydrofolate and a 10-fold decrease in the rate of hydride transfer (85 s-1) from NADPH to dihydrofolate. The elevated rate of tetrahydrofolate release upon the rebinding of NADPH, a characteristic of the wild-type enzyme-catalyzed reaction, is diminished. The intrinsic pKa (6.4) of the mutant enzyme binary complex with NADPH is similar to that of the wild type, but the pKa of the ternary complex is increased to 7.3, about on pH unit higher than the wild-type value. Further mutagenesis (G51P and an insertion of K52) was conducted to incorporate a hairpin turn unique to the C-terminus of the alpha C-helix of the L. casei enzyme in order to adjust a possible dislocation of the new helix. The resultant pentamutant enzyme shows restoration of many of the kinetic parameters, such as kcat (12 s-1), KM (1.1 microM for dihydrofolate), and khyd (526 s-1), to the wild-type values. The synergism in the product release is also largely restored. A substrate-induced conformational change responsible for the fine tuning of the catalytic process was found to be associated with the newly installed hairpin structure. The Asp27 residue of the mutant enzyme was found to be reprotonated before tetrahydrofolate release.

Amino Acid Sequence↗
PubMed1991

Microdissection of human high resolution banded chromosome, polymerase chain reaction and microcloning.

A simple technique for microdissection of specific region of human high resolution banded chromosome, followed by polymerase chain reaction (PCR), and microcloning was successfully used to microdissect 4 chromosomal pieces from the distal one third from band 11.2 to the terminal of the short arm of Y chromosome where the testis determining factor is located; 3.6 x 10(4) clones were obtained after 30 cycles of PCR. We analysed 41 clones with insert. The size of insert ranges from 140 to 350 bp (average 250 bp). A Southern blot analysis was done for one of them, and a 2.5 kb Hind III fragment was detected.

Cloning, Molecular↗
PubMed1991

[Clinical use of polysomnography (PSG)].

The clinical diagnoses in 695 cases using PSG were analysed. The results are as follows: Obstructive sleep apnea syndrome (OSAS) in 482 cases (69.4%), chronic obstructive pulmonary diseases with nocturnal hypoxemia in 25 cases (3.6%), epilepsy in 31 cases (4.5%), other sleep disorders in 5 cases (0.7%), and essentially normal in 152 cases (21.9%). Some parameters of PSG in 65 cases with OSAS and those in 2 cases before and after treatment were analysed. It is emphasized that PSG is using for diagnosis of different types of OSAS with appraisable seriousness and of other related sleep disorders. The method and indications of PSG were discussed.

Electroencephalography↗
PubMed1991

[Lymphomatoid granulomatosis. A report of 2 cases].

Two patients with lymphomatoid granulomatosis were diagnosed by postmortem autopsy or exploratory thoracotomy. The lung, skin, spleen, renal and lymph nodes were involved. The most common presenting complaints are fever, cough, expectoration shortness of breath. The radiographic manifestations are multiple, bilateral nodular shadows. The histologic features is a unique form of pulmonary angiitis and granulomatosis, which is a necrotizing angiocentric and angio-destructive infiltrative process composed of small lymphocytes and atypical lymphoreticular cells.

Adult↗
PubMed1991

[An analysis of 30 cases of chylothorax and chyloperitoneum].

Thirty patients diagnosed as chylothorax and chyloperitoneum (13 of chylothorax, 9 of chyloperitoneum and 8 of both) in PUMC Hospital from 1923 to 1989 were reported. Thus, the incidence rate of these two diseases is rather low. The commonest causes were iatrogenic trauma (9 cases) and malignant tumor (7 cases). Other causes were tuberculosis (5 cases), lymphangioma (2 cases), Behcet's syndrome (1 case) and non-iatrogenic trauma (1 case). The etiology was not known in 5 cases. Acute episode was observed in patients with traumatic chylous effusion; it was usually manifested as dyspnea or abdominal distention. Patients with nontraumatic chylous effusion usually run a chronic course. The characteristics of chylous effusion were analyzed. Lymphangiography and lymphoscintigraphy with 99m TC-labeled dextran play important roles in diagnosis and treatment. It has been suggested that the changes in T-cell immunocompetence is important in determining whether the treatment should be conservative or operative. If chylous effusion is due to tuberculosis, antituberculosis treatment should be instituted.

Adolescent↗
PubMed1990

A reliable method for obtaining high-resolution banded chromosome preparations from chorionic villus samples.

A reliable method for obtaining high-resolution banded chromosome preparations from chorionic villus samples (CVS) is described, in which a synchronization cell-culture technique with the use of thymidine is introduced. After culturing a suspension of chorionic villus cells in a medium supplemented with 0.3 mg/ml thymidine for 13-17 hr, cells were washed twice, and recultured for further 8 hr. The cells were then treated with 10 micrograms/ml ethidium bromide or 1 microgram/ml actinomycin D for 1 hr and subsequently with 0.01 microgram/ml Colcemid for 30 min. The average mitotic index obtained was more than 60 mitoses/mg CVS, and more than 60% of mitoses proceeded to the prometaphase stage, the later prophase stage, or in between. The application of this method for prenatal diagnoses in five CVS in the first trimester pregnancies proved that it is a simple, practical and efficient prenatal diagnostic method.

Cell Cycle↗
PubMed1990

Economic effects of nosocomial infections in cardiac surgery.

A study of 60 infected patients and matched controls showed that nosocomial infection in cardiac surgery cost each patient an additional 2207 yuan (pounds 290). The cost of multisite infection was much higher. Infected patients were in hospital for a mean of 14 extra days.

Adolescent↗
PubMed1990

A prospective study of nosocomial infections in cardiac surgery patients in China.

A prospective survey of postoperative nosocomial infections (NI) in cardiac surgery was carried out in a cardiovascular specialty hospital in Beijing, China. During the period from December 1986 to December 1987, 1208 cardiovascular surgery patients were surveyed for NI. The overall incidence of NI was found to be 7.5%. The incidence of lower respiratory tract and wound infections were 4.5% and 2.9%, respectively. These two kinds of infection accounted for 78.1% of the total infections. After effective control measures were taken at the end of the first 6 months (December 1986 to May 1987) of the study, the incidence fell from 10.6% to 5.1% in the next 7-month period (June to December 1987). The pathogens causing NI were mostly gram-negative bacteria, and they were mainly opportunistic. The contribution of fungal infection was significant in the hospitals. The majority of the pathogenic isolates were highly resistant to the antibiotics commonly used in the hospital.

Adolescent↗