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Biomedical subjects

Jun Long

Publications and source records attributed to Jun Long.

9 recordsLinked to original sources
PubMed2007

Enantioselective Michael addition of alpha-substituted cyanoacetates to vinyl ketones catalyzed by bifunctional organocatalysts.

A highly enantioselective Michael addition of alpha-substituted cyanoacetates to vinyl ketones was accomplished in the presence of simple bifunctional thiourea/tertiary amine organocatalysts. A number of alpha-aryl or alkyl cyanoacetates have been successfully applied to give multifunctional compounds with an all-carbon-substituted quaternary stereocenter in excellent enantioselectivities (82-97 % ee) and yields (61-99 %). The optical pure adducts could be smoothly converted to variously structured beta(2,2)-amino acid esters. Moreover, an interesting reaction model involving multiple hydrogen-bonding interactions amongst the thiourea/tertiary amine catalyst and the reactants has been proposed based on the absolute configuration of the adduct and computational studies.

Acetates↗
PubMed2006

Colloidal interactions between Langmuir-Blodgett bitumen films and fine solid particles.

In oil sand processing, accumulation of surface-active compounds at various interfaces imposes a significant impact on bitumen recovery and bitumen froth cleaning (i.e., froth treatment) by altering the interfacial properties and colloidal interactions among various oil sand components. In the present study, bitumen films were prepared at toluene/water interfaces using a Langmuir-Blodgett (LB) upstroke deposition technique. The surface of the prepared LB bitumen films was found to be hydrophobic, comprised of wormlike aggregates containing a relatively high content of oxygen, sulfur, and nitrogen, indicating an accumulation of surface-active compounds in the films. Using an atomic force microscope, colloidal interactions between the LB bitumen films and fine solids (model silica particles and clay particles chosen directly from an oil sand tailing stream) were measured in industrial plant process water and compared with those measured in simple electrolyte solutions of controlled pH and divalent cation concentrations. The results show a stronger long-range repulsive force and weaker adhesion force in solutions of higher pH and lower divalent cation concentration. In plant process water, a moderate long-range repulsive force and weak adhesion were measured despite its high electrolyte content. These findings provide more insight into the mechanisms of bitumen extraction and froth treatment.

Journal Article↗
PubMed2006

Adhesion of single polyelectrolyte molecules on silica, mica, and bitumen surfaces.

In a recent study (Energy Fuels 2005, 19, 936), a partially hydrolyzed polyacrylamide (HPAM) was used as a process aid to recover bitumen from oil sand ores. It was found that HPAM addition at the bitumen extraction step not only improved bitumen recovery but also enhanced fine solids settling in the tailings stream. To understand the role of HPAM, single-molecule force spectroscopy was employed for the first time to measure the desorption/adhesion forces of single HPAM molecules on silica, mica, and bitumen surfaces using an atomic force microscope (AFM). Silicon wafers with an oxidized surface layer and newly cleaved mica were used, respectively, to represent sand grains and clays in oil sands. The force measurements were carried out in deionized water and in commercial plant process water under equilibrium conditions. The desorption/adhesion forces of HPAM obtained on mica, silica, and bitumen surfaces were approximately 200, 40, and 80 pN in deionized water and approximately 100, 50, and 40 pN in the plant process water, respectively. The measured adhesion forces together with the zeta potential values of these surfaces indicate that the polymer would preferentially adsorb onto clay surfaces rather than onto bitumen surfaces. It is the selective adsorption of HPAM that benefits both bitumen recovery and tailings settling when the polymer was added directly to the bitumen extraction process at an appropriate dosage.

Acrylic Resins↗
PubMed2005

[A field trial for evaluating the safety of recombinant human interferon alpha-2b for nasal spray].

OBJECTIVE: To evaluate the safety of recombinant human interferon alpha-2b for nasal spray for the prevention of SARS and other upper respiratory viral infections. METHODS: Field epidemiologic evaluation was conducted, the design was randomized and had a synchronously parallel control group. In the study, the drugs were given for five days and all subjects were followed up for ten days. RESULTS: During the period of using interferon, body temperature of the experimental group was normal compared to the control group. Experimental group had more influenza-like symptoms than the control group (P < 0.05), such as headache (4.83%-7.09%), dizziness (7.17%-11.63%), lassitude (8.55%-15.06%), muscular soreness (4.43%-7.09%), pharynx dryness (12.10%-17.85%), angina (6.25%-8.72%), abdominal pain (2.30%-5.50%) and diarrhea (2.45%-5.66%). Most of side effects reached their peak with in the first 3 days. Except for pharynx dryness, the incidences of all other side effects declined after completion of the use of the trial drug, and incidences of some symptoms in experimental group were lower than those of the control group. There were no significant differences in the symptoms of cough and expectoration between the experimental group and the control group. The incidence of exanthem in the control group was significantly higher than that in the experimental group. The side effect of bloody nasal mucus was not observed in experimental group, which had been reported by other authors in several volunteer studies. CONCLUSION: Using recombinant human interferon alpha-2b for nasal spray could lead to some influenza-like symptoms, however, all those symptoms were mild , reversible, and relieved after completion of the use of the trial drug. No serious side effects were found during the period of following up. The authors conclude that the drug is safe.

Abdominal Pain↗
PubMed2004

[Drug-resistance analysis of Gram-negative bacilli producing extended-spectrum beta-lactamases in lower respiratory tract infection].

OBJECTIVE: To analyze occurrence of Gram-negative bacteria producing extended-spectrum beta-lactamase (ESBL) in patients with lower respiratory tract infection and assess their drug sensitivity to provide evidence for clinical management of lower respiratory tract infection with drug-resistant ESBL-producing bacteria. METHODS: A total of 312 Gram-negative bacterial strains were isolated from patients with lower respiratory tract infection and identified for the presence of ESBL by Vitek ESBL detection test and double-disk synergy tests as well as standard disk diffusion test. The effects of 10 antibacterial drugs on ESBL-producing strains were compared. RESULTS: A rate of 20.1% of the isolated strains were identified to produce ESBLs, including Klebsiella Pneumoniae, Escherichia coli, Enterobacter cloacae, Pseudomonas aeruginasa and Klebsiella oxytocla (accounting for 30.1%, 29.1%, 27.0%, 11.3%, and 2.5%, respectively, of the ESBL-producing strains). Imipenem possessed the most powerful antibacterial activity against ESBL-producing strains. CONCLUSIONS: Attention should be given to lower respiratory tract infections with ESBL-producing Gram-negative bacilli, and imipenem can be the primary choice for fighting such infections.

Drug Resistance, Bacterial↗
PubMed2003

[Bacteriostasis of iodoform in vivo and in vitro].

OBJECTIVE: To investigate the bacteriostasis of iodoform in vivo and in vitro. METHODS: Bacteriostasis of iodoform and economycin against different species of bacteria was observed in vitro and the curves of bacteriostasis were obtained for each agent. In rabbit models traumatic liver injury complicated by infection of the wounds with Staphylococcus aureus, Escherichia coli and Pseudomonas aerudomonas, common bandage supplemented respectively with 6% iodoform, 10% iodoform, economycin ointment, and saline were applied for wound addressing and the changes in the number of bacterium in the wounds was measured 1, 3, and 7 days later, respectively. RESULTS: Iodoform showed better bacteriostatic effect than economycin in inhibiting the growth of the majority of the aerobic bacteria in vitro, and its action on anaerobic bacteria appeared similar to the effect of economycin. In rabbit models, iodoform at the concentration of 10% showed significantly better bacteriostatic effect against the 3 species of bacteria than economycin (P<0.01). CONCLUSION: Iodoform possesses more potent bacteriostatic effect than economycin against most bacteria.

Animals↗
PubMed2003

[Study on the relationship between changes of adrenomedulin in plasma and vascular resistance during traumatic shock in rats].

OBJECTIVE: To observe the changes of adrenomedulin in plasma and vascular resistance during traumatic shock in rats. METHODS: The concentration of adrenomedulin in plasma of rats after traumatic shock was detected by radio immunization. Mean arterial pressure, total peripheral vascular resistance (TPVR) and cardiac index (CI) were estimated by electrical conductance method. RESULTS: The concentration of adrenomedulin in plasma of traumatic shock without resuscitation group (68.34+/-3.71)ng/L and traumatic shock with resuscitation group (146.27+/-9.83)ng/L were higher than that of control group(32.63+/-7.55)ng/L (P<0.01 and P<0.05). TPVR of traumatic shock with resuscitation group (10.57+/-0.35) kPa.s.L-1 was lower than that of traumatic shock without resuscitation group (16.75+/-0.23) kPa.s.L-1(P<0.01) and its CI (215.59+/-1.29) ml.min-1.kg-1 was higher than that of traumatic shock without resuscitation group (143.11+/-0.86) ml.min-1.kg-1 (P<0.01). CONCLUSION: Adrenomedulin is closely correlated with changes of vascular resistance and plays an important role during pathophysiological processes in rats after traumatic shock.

Adrenomedullin↗
PubMed2003

[Epidemiological study of the features of the index cases in SARS case clusters].

OBJECTIVE: To understand the epidemiological characteristics of the index cases in severe acute respiratory syndrome (SARS) cases clusters and to evaluate their importance in the whole epidemic process of SARS. METHODS: Data of the index SARS cases and the subsequent case clusters were collected by means of face-to-face interview in combination with field investigation and case history consultations. RESULTS: In all three SARS clusters, the index cases all had chronic disease and played the role of infection source that transmitted the virus to the patients' family members, attending medical staff as well as other non-SARS patients sharing the same ward with them. CONCLUSION: The index cases played an important role in transmission of SARS virus among the case clusters, and their infective stages are confined within certain phases of the disease course.

Adult↗