Biomedical subjects

N Li

Publications and source records attributed to N Li.

At least 307 records · Page 17Linked to original sources

PubMed1997

Microbiological factors influencing the outcome of nosocomial bloodstream infections: a 6-year validated, population-based model.

All patients (n = 1,745) with nosocomial bloodstream infection identified between 1986 and 1991 at a single 900-bed tertiary care hospital were studied to identify microbiological factors independently associated with mortality due to the infection. Patients were identified by prospective, case-based surveillance and positive blood cultures. Mortality rates were examined for secular trends. Prognostic factors were determined with use of univariate and multivariate analyses, and both derivation and validation sets were used. A total of 1,745 patients developed nosocomial bloodstream infection. The 28-day crude mortality was 22%, and crude in-hospital mortality was 35%. Factors independently (all P < .05) associated with increased 28-day mortality rates were older age, longer length of hospital stay before bloodstream infection, and a diagnosis of cancer or disease of the digestive system. After adjustment for major confounders, Candida species were the only organisms independently influencing the outcome of nosocomial bloodstream infection (odds ratio [OR] for mortality = 1.84; 95% confidence interval [CI], 1.22-2.76; P = .0035). The two additional microbiological factors independently associated with increased mortality were pneumonia as a source of secondary infection (OR = 2.74; 95% CI, 1.87-4.00; P < .0001) and polymicrobial infection (OR = 1.68; 95% CI, 1.22-2.32; P = .0014). Our data suggest that microbiological factors independently affect the outcome of nosocomial bloodstream infection.

Adult↗

PubMed1997

Effects of serotonin on platelet activation in whole blood.

Serotonin (5-hydrotryptamine, 5-HT) is a weak platelet agonist, which has not been evaluated fully with respect to platelet responses in whole blood. We thus re-evaluated platelet responses to 5-HT using three whole blood techniques: flow cytometry, impedance aggregometry and filtragometry. At concentrations up to 10(-5) mol/l, 5-HT per se failed to induce platelet aggregation in whole blood, or to increase platelet fibrinogen binding or P-selectin expression. However, 5-HT potentiated platelet responses to low concentrations of adenosine diphosphate (ADP) or thrombin dose-dependently. 5-HT (10(-7), 10(-6) and 10(-5) mol/l) increased ADP-induced platelet fibrinogen binding by 40, 59 and 79%, while P-selectin expression increased by 45, 64 and 95%, respectively (P < 0.05; n = 10). The enhancing effects of 5-HT were even more pronounced in thrombin-stimulated samples, as 5-HT at 10(-8), 10(-7), 10(-6) and 10(-5) mol/l increased fibrinogen binding by 56, 128, 212 and 260% (P < 0.05), and P-selectin expression by 31, 56, 89 and 109%, respectively (P < 0.01; n = 10). The response to 5-HT was inhibited dose-dependently by a highly selective 5-HT2A receptor antagonist (SR 46349), with almost complete inhibition at 10(-6) mol/l. Impedance aggregometry showed a significant enhancement in 5 x 10(-6) mol/l ADP-induced platelet aggregation caused by 5-HT at 8 x 10(-8) mol/l (from 7.58 +/- 2.50 omega to 9.02 +/- 2.43 omega, P < 0.02, n = 12). Similarly, filtragometry readings, i.e. the time taken for platelet aggregates to occlude a microfilter, were shortened by 27% (P < 0.05, n = 9), reflecting increased platelet aggregability. Our data suggest that 5-HT per se does not activate platelets, but dose-dependently enhances platelet activation induced by ADP and, in particular, thrombin in whole blood. Thus, the idea that 5-HT is a 'helper agonist' is supported; this effect is mediated by 5-HT2A receptors.

Adenosine Diphosphate↗

PubMed1997

[Isolation of Legionella pneumophila from 24 hr-home bath water and an eradication trial of the bacteria from the bath].

Contamination of 24 hr home bath with Legionella pneumophila is recently well recognized. Eradication of the water-bath contamination from L. pneumophila and other bacteria is an important matter to prevent the infection because the 24 hr-bathing facility is widely accepted in Japanese houses. Among the 16 bathing water samples we tested, Legionella pneumophia was isolated from 6 cases (37.5%) when the bathing water was not treated with disinfectants. Number of L. pneumophila increased up to 10(3) cfu/ml and total culturable bacterial counts reached to 10(5) cfu/ml within 5 days when the water was not treated. We selected 5 water baths among 6 positive cases to study the bactericidal effect of chlorine. As a result we concluded that the growth of L. pneumophila in 24 hr-water bath could be stopped by the 2 ppm chlorination program every day.

Baths↗

PubMed1997

[Primary renal epithelioid angiosarcoma with transitional cell carcinoma in renal pelvis].

To understand the clinical characteristics of primary renal epithelioid angiosarcoma. We used clinical pathology, immunohistochemistry and electron microscopy. Analysis and discussion about the case were combined with a review of the literature. We first report a female case of the left renal epithelioid angiosarcoma and concomitantly, transitional cell carcinoma developing from the renal pelvis at age 69. Epithelioid angiosarcoma showed positive results for FVIIIRA+, UEA, CD31, Cytokeratin and EMA. Weibel-Palade bodies were identified by electron microscopy. Primary renal epithelioid angiosarcoma was a rare clinical entity with a poor prognosis, which mimics epithelial tumor, both morphologically and immunohistochemically, and may be lead to misdiagnosis. The combined use of endothelial cell markers including FVIIIRA, CD31, UEA and electronmicroscopy can confirm the diagnosis of this neoplasm.

Aged↗

PubMed1997

[Observation of the free calcium of lens epithelial cell using laser scanning confocal microscopy].

OBJECTIVE: Using a new fluorescent Ca++ indicator (fluo-3) and laser scanning confocal microscopy (LSCM) to monitor the intracellular Ca++ of rat lens epithelial cell (LEC). METHODS: The LEC was loaded with fluo-3, then the distribution of free Ca++ in the LEC was observed by using LSCM monitoring the distribution of fluorescence that is given due to the chelation between fluo-3 and Ca++. At last, ionophore (A23187) and heavy-metal ions (Mn++) were applied to calibrate fluo-3 intensities to obtain [Ca++]i value. RESULTS: The free calcium in LEC is mainly located in the nucleus. Free calcium concentration of rat LEC is 259.79 +/- 49.24 nmol/L. CONCLUSION: Fluo-3 can be loaded into LEC by incubation with acetoxymethyl (AM) ester of the dye, and LSCM can be used to observe the cellular free calcium directly by surveying the fluorescence. This method will pave a way technically for the further study of intracellular free Ca++ of the LEC.

Animals↗

PubMed1997

[Calcium mobilization and influx induced by extracellular ATP in the lens epithelial cells].

OBJECTIVE: To examine the effects of extracellular ATP application on the intracellular Ca++ concentration of the in vitro lens epithelial cells (LECs). METHODS: LECs were loaded with fluo-3, then the changes of fluorescent intensities in different conditions were observed by laser scanning confocal microscopy (LSCM). RESULTS: Normal in vitro LECs have strong response to 100 mumol/L ATP and a biphasic wave rise is shown, but LECs have no apparent response to low concentration ATP. When the extracellular calcium chelates to ethylene glycol bis (2-aminoethyl) ether tetracetic acid (EGTA), ATP stimulates the cells and the response is a rapid monophasic rise. CONCLUSION: ATP can induce calcium mobilization and entry into LECs loaded with fluo-3 in a dose-dependent manner. In the LEC membrane, possibly there are P2-purinoceptors.

Adenosine Triphosphate↗

PubMed1997

[Nutritional rehabilitation for patients with extreme short bowel].

The prolonged parenteral nutrition and intestinal transplantation is considered as useful therapeutics for patients with extreme short bowel. However, both of them are still limited. We report the results of nutritional rehabilitation for patients with extreme short bowel. Three patients whose residual intestines were 65 cm, 75 cm and 30 cm respectively were treated with growth hormone, glutamine and a fiber-containing diet for 2-3 weeks. The nutritional status of patients and the absorptive ability of residual intestine in these patients improved obviously after the treatment. This nutritional rehabilitation regime offers a new potential method for patients with short bowel syndrome.

Aged↗

PubMed1997

[Experience and lessons of lung transplantation].

In the last 2 years, four hospitals performmed cooperatively single-lung transplantation for 3 patients, 1 left lung and 2 right lung. The patients had pulmonary fibrosis, COPD with cancer or tuberculosis, infection in some extent before transplantation. The patients died from severe infection 9, 48 and 43 days after the operation. We discussed the selection of donors and recipients, operative procedures, postoperative management, especially monitoring, differential diagnosis and treatment of infection and rejection. HLA compatibility and transbronchial lung biopsy were important to the success of lung transplantation. We believe that rejection and infection are important causes of short-term death that should be given more attention.

Graft Rejection↗

PubMed1997

[Determination of soluble interleukin-2 receptor levels in patients with allergic rhinitis].

To explore the regulatory mechanism of the soluble interleukin-2 receptor (SIL-2R) in patient allergic rhinitis, SIL-2R levels in serum and nasal secretion were detected in 39 patients with allergic rhinitis, 19 patients with chronic rhinitis and 15 normal controls, The determination of SIL-2R was done by a sandwich ELISA method. The results showed that the SIL-2R concentrations in patients with allergic rhinitis were significantly higher than those of the controls (P < 0.001). These results suggest that SIL-2R may play an important role in allergic rhinitis.

Adolescent↗

PubMed1997

[Value of nasopharyngofiberoscope, spectrography and computer in diagnosis and treatment of pathologic speech after cleft palate operation].

The speech of 45 cases with velopharyngeal incompetence (VPI) were evaluated by combining application of nasopharyngofiberoscope (NPF) and computer-spectrographic analysis system (CSAS) after cleft palate operation and conservative speech therapy with using cleft palate obturators. The results showed: Improving rate of velopharyngeal incompetence (IRVPI) was close to 33.33% after 2.5-3 years therapy. The spectrographic analysis showed a clearer, and darken frequency band, normal resonance peaks (F2,F3) and seldom appearance of negative value of voice origination time (VOT). The above indicated that patients had achieved adequate velopharyngeal competence (VPC) and good speech habit. It has important significances and greatly improve speech therapy level to apply NPF and CSAS to analysing pathologic speech and evaluating therapic effect.

Adolescent↗

PubMed1997

Identifying the hospitalized patient at risk for nosocomial bloodstream infection: a population-based study.

Included in a 3-year population-based study were all patients (n = 64,281) admitted to a single tertiary care hospital (902 beds) using prospective hospital-wide surveillance for nosocomial infections. The objective of the study was to identify patients at risk for nosocomial bloodstream infection by using readily available hospital admission variables. After identifying potential risk factors for infection by univariate analyses, we derived multivariate models for predicting bloodstream infection by using logistical regression procedures. A total of 931 patients (1.45 per 100 admissions) developed a nosocomial bloodstream infection (2.2 episodes per 1000 patient-days) between 1 July 1987, and 30 June 1990. The crude mortality among infected patients was 34%, and the 319 deaths represented 22% of the total in-hospital mortality. Independent predictors of bloodstream infection were age, gender, primary diagnosis, and admission to a critical care unit. The sensitivity and specificity of the models for classifying patients as infected or noninfected were 81% and 81% for infants (1-11 months old) and 72% and 72% for adults, respectively. The negative predictive value of both models exceeded 99%. Applied to all patients on admission, the models we developed allowed us to survey only 28% of patients to identify more than 70% of those who will develop a nosocomial bloodstream infection.

Adolescent↗

PubMed1997

X-ray crystal structure of cytotoxic oxidized cholesterols: 7-ketocholesterol and 25-hydroxycholesterol.

The cytotoxic cholesterol derivative, 7-ketocholesterol, crystallizes in a monoclinic unit cell, space group P2(1) with a = 11.405 A, b = 6.288 A, c = 35.393 A and beta = 92.75 degrees (Z = 4). Its room temperature crystal structure was solved by direct methods, i.e., the minimal principle via the Shake-and-Bake (SnB) algorithm. In contrast to the continuous chain pattern found for the cholesterol monohydrate structure, hydrogen bonding in the 7-ketocholesterol structure is localized to specific sites via one water molecule that forms linkages between two O3 hydroxyl groups and one keto oxygen. The final weighted R factor for 4562 reflections was 0.144. The 25-hydroxycholesterol also crystallizes in a monoclinic unit cell (P2(1)), with a = 10.840 A, b = 14.533 A, c = 16.093 A and beta = 95.91 degrees (Z = 4). The low temperature structure was solved by DIRDIF. In this instance, molecular packing is anti-parallel in layers stabilized by hydrogen bonding networks via both hydroxyl functions, differing both from cholesterol monohydrate and the 7-ketocholesterol. The final weighted R-factor for 6566 reflections was 0.034. Functional differences of the oxysterols therefore, may be expressed by observed variations in the molecular packing and geometry.

Crystallization↗

PubMed1997

[Platelet calcium oscillation by laser scanning confocal microscopy].

OBJECTIVE: To observe platelet calcium oscillation and the influence of extracellular Ca2+ on it. METHODS: We observed a single platelet intracellular Ca++ change and the influence of extracellular Ca2+ on it by laser sanning confocal microscopy when various agonists of different concentrations stimulated platelets. RESULTS: The other agonists except thrombin induced platelet calcium oscillation. With increasing agonis concentrations, the frequence of calcium oscillation enhanced and calcium oscillation sustained longer. In the absence of Ca++, the amplitude of ADP-induced calcium oscillation was smaller without frequence variations, and 5-TH induced calcium oscillation was inhibited. CONCLUSIONS: Platelet calcium oscillation increased from fluctuation either in the entry of external calcium or the release from internal stores.

Adenosine Diphosphate↗

PubMed1996

A novel bifunctional fusion enzyme catalyzing ethylene synthesis via 1-aminocyclopropane1-carboxylic acid.

A C terminus truncated soybean 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (466 aa) was fused to an N terminus truncated tomato ACC oxidase (312 aa) to create a 778-amino acid fusion polypeptide. This ACC synthase-ACC oxidase fusion enzyme (ACSO) was expressed in a heterologous prokaryotic Escherichia coli system, which is capable of converting endogenous S-adenosyl-L-methionine (AdoMet) to ethylene. The molecular weight of the fusion enzyme, ACSO, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was 90 +/- 3 kDa. Gel filtration analysis indicates that the native ACSO is oligomeric and is capable of converting exogenously supplied AdoMet to ethylene. The ethylene production rate of ACSO fusion enzyme was determined to be 6.0 nmol h-1 mg-1 under our assaying conditions using the partially purified enzyme extract. In the enzyme reaction mixture, an increase in ethylene production catalyzed by the bifunctional ACSO was accompanied by a decrease in ACC accumulation. Similarly, in E. coli cells, the level of ACC, produced as an intermediate during the sequential reactions from AdoMet to ethylene, was also found to arise earlier than that of ethylene. Because ACSO could produce ethylene from the ubiquitous AdoMet in living cell and the method commonly used to measure gaseous ethylene is simple, fast, and sensitive, we anticipate this bifunctional fusion enzyme to be useful as a reporter and for research in molecular biology, developmental biology, fermentation, and genetic engineering.

Amino Acid Oxidoreductases↗

PubMed1996

Phosphorylation of the proteasome activator PA28 is required for proteasome activation.

PA28, also referred to as 11S regulator, is a potent activator of the peptidase activities of the proteasome (multicatalytic proteinase complex). Although the role(s) of PA28-20S proteasome complexes in cellular proteolytic processes remain to be defined, these particles have been implicated in antigen processing of major histocompatibility complex (MHC) class I molecules. Our results demonstrate that PA28 is phosphorylated as evidenced by 32P incorporation into a single PA28 species in rabbit reticulocytes. In reticulocytes as well as human erythrocytes, PA28 is normally found in a phosphorylated state as detected by phosphoserine antibody. In human erythrocytes, this antibody recognizes three polypeptides which are also detected by antibody to PA28 on Western blot analysis. Dephosphorylation with alkaline phosphatase treatment completely abolishes the ability of PA28 to activate hydrolysis of Suc-Leu-Leu-Val-Tyr by proteasomes. After exposure to phosphatase, the three polypeptides are no longer recognized by phosphoserine antibody, although binding to PA28 antibody is unaffected. These results suggest that phosphorylation may function in transduction of cytokine and growth factor signals that, in turn, modulate antigen presentation and other processes which involve PA28-20S proteasome complexes.

Amino Acid Sequence↗

PubMed1996

Fluorometric determination for micro amounts of albumin and globulin fractions without separation by using alpha, beta, gamma, delta-tetra(4'-carboxyphenyl)porphin.

A simultaneous determination of micro amounts of albumin and globulin fractions by fluorometry with only reagent alpha,beta,gamma,delta-tetra(4'-carboxyphenyl)porphin (TCPP) in the aqueous solution has been developed. Under the experimental conditions (5.6 x 10(-7) mol/liter of TCPP, pH 3.0, and at room temperature), the linear range of this assay was 0.09-12 microgram/ml and the detection limits (3 S/N) were 60 ng/ml for albumin and 90 ng/ml for globulin, respectively. The human serum samples were measured satisfactorily by using this method.

Artifacts↗

PubMed1996

Effects of N-terminal deletions on 1-aminocyclopropane-1-carboxylate synthase activity.

A series of nested N-terminal deletions were made on the full-length (wt) and C-terminal deleted (Cdel) 1-aminocyclopropane-1-carboxylate synthase cDNAs. These wt and mutant ACC synthases were over-expressed in a heterologous E. coli expression system. It was found that removal of an amino acid region (residues 2-12) from the non-conserved N-termini of wt and Cdel ACC synthases led to a slight increase in both in vivo ACC production and in vitro ACC synthase activity. Further deletion of 11 amino acids through Glu-23 from the N-termini of both wt and Cdel ACC synthases resulted in a substantial reduction in both in vivo ACC production and in vitro enzyme activity. Deletion of an amino acid region, residues 3 through 27, from the N-terminus of ACC synthase abolished enzyme activity completely. Kinetic analysis of a highly purified double-deletion mutant (NCdel-1) of ACC synthase demonstrated that the Km of this mutant is 42 microM, which is much smaller than that of the corresponding Cdel (280 microM) and closer to that of wt (22 microM) reported previously, suggesting a clear effect of the non-conserved N-terminal region on its ACC synthase function.

Amino Acid Sequence↗

PubMed1996

Characterization of crystals of Penicillium purpurogenum acetyl xylan esterase from high-resolution x-ray diffraction.

Acetyl xylan esterase from Penicillium purpurogenum, a single-chain 23 kDa member of a newly characterized family of esterases that cleaves side chain ester linkages in xylan, has been crystallized. The crystals diffract to better than 1 A resolution at the Cornell High Energy Synchrotron Source (CHESS) and are highly stable in the synchrotron radiation. The space group is P2(1)2(1)2(1) and cell dimensions are a = 34.9 A, b = 61.0 A, C = 72.5 A.

Acetylesterase↗