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Biomedical subjects

J G Xu

Publications and source records attributed to J G Xu.

At least 19 recordsLinked to original sources
PubMed2005

Marked hypotension induced by adrenaline contained in local anesthetic.

OBJECTIVES: Local anesthetics containing adrenaline, which often cause cardiovascular side effects, are routinely used in functional endoscopic sinus surgery (FESS) for the main purpose of hemostasis. The controversies concerning hemodynamic effects of adrenaline in local infiltration are widely discussed, but there is no definite conclusion. A prospective, randomized, double-blinded study was carried out to discover the hemodynamic effects after local infiltration of 1:200,000 adrenaline contained in 2% lidocaine under general anesthesia. STUDY DESIGN: Seventy-six adult patients undergoing FESS during general anesthesia were allocated randomly into three groups. Group I patients (n = 26) received 2% lidocaine 2 mL with adrenaline (1:200,000), group II patients (n = 25) received saline 2 mL with adrenaline (1:200,000), and group III patients (control group, n = 25) received saline 2 mL without adrenaline for local infiltration. Electrocardiogram (ECG) and heart rate (HR) were monitored simultaneously; systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial blood pressure (MAP) were directly measured in radial artery continuously after local infiltration. METHODS: SBP, DBP, MAP, and HR were recorded at 10 time points: before infiltration (baseline), 0.5 minutes, 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minute, and 5 minutes after infiltration. RESULTS: Significant hemodynamic changes, particularly hypotension (P < .01), after local infiltration were observed in group I and group II compared with the baseline, but not in group III. However, there were no significant hemodynamic changes between group I and group II at the same time points (P > .05). The significant hemodynamic changes lasted no longer than 4 minutes. CONCLUSIONS: Lidocaine (2%) or saline with adrenaline (1:200,000) does cause temporary hypotension and other hemodynamic changes during general anesthesia, which last no longer than 4 minutes. The causative mechanism is caused by the effect of adrenaline. This is a preliminary study.

Anesthesia, General↗
PubMed2005

Methemoglobinemia misdiagnosed as ruptured ectopic pregnancy.

A 22-year-old woman with an initial diagnosis of 'ruptured ectopic pregnancy' and 'hemorrhagic shock' was sent to the operation room for surgical treatment. The mucocutaneous color was deeply cyanosed and the pulse oximeter oxygen saturation (SpO2) was only 86% after tracheal intubation (100% O2). 'Chocolate-brown' blood was observed and methemoglobinemia was considered. Then the arterial blood gas (ABG) sample was obtained, an intravenous infusion of methylene blue and vitamin C followed. The patient recovered quickly, and later two other patients with similar symptoms were treated in the same way. The success was due to a correct diagnosis accompanied with prompt treatment and quick recognition of the etiology.

Adult↗
PubMed2005

Effects of hydroxyethyl starch on hepatic production of cytokines and activation of transcription factors in lipopolysaccharide-administered rats.

BACKGROUND: Hydroxyethyl starch (HES) is one of the most frequently used plasma substitutes. Some studies have indicated that HES may have anti-inflammatory effects. The present in vivo study was performed to investigate the effects of HES on hepatic production of cytokines and activation of transcription factors in sepsis. METHODS: Adult male Sprague-Dawley rats were randomly divided into four groups: rats challenged with lipopolysaccharide (LPS) (5 mg kg(-1)) and treated with saline (64 ml kg(-1)); challenged with LPS (5 mg kg(-1)) and treated with HES (16 ml kg(-1)); injected with saline and treated with HES (16 ml kg(-1)); and saline control. Each hepatic tissue was collected in groups of rats 2 h after induction of endotoxemia for determination of tumour necrosis factor (TNF)-alpha levels, TNF-alpha mRNA expressions, and nuclear factor (NF)-kappaB, activator protein (AP)-1 activities or 3 h after LPS challenge for IL-1beta, IL-6, IL-8, IL-10 levels and the mRNA expressions. RESULTS: Endotoxemia was associated with significant increases in hepatic proinflammatory cytokine productions and transcription factor activities. HES significantly reduced the increased hepatic levels of TNF-alpha, IL-1beta, IL-6, IL-8 and the mRNAs in the endotoxemic rats. Similarly, HES could inhibit hepatic NF-kappaB and AP-1 activations. CONCLUSION: The results suggest that in sepsis HES may down-regulate hepatic inflammatory mediators production and these anti-inflammatory effects may act through inhibition of NF-kappaB and AP-1 activations.

Animals↗
PubMed2005

Influence of hydroxyethyl starch on lipopolysaccharide-induced tissue nuclear factor kappa B activation and systemic TNF-alpha expression.

BACKGROUND: Several studies have shown beneficial effects of hydroxyethyl starch (HES) on organ damage in the treatment of severe inflammatory situations, but the mechanisms remain unclear. Nuclear factor-kappa B (NF-kappaB) activation is known to contribute to many aspects of inflammatory injury and organ dysfunction in critical illness, and tumor necrosis factor-alpha (TNF-alpha) is considered the most important pro-inflammatory cytokine. The present study was undertaken to test whether HES (200/0.5) has some effects on tissue NF-kappaB activity and systemic TNF-alpha expression induced by lipopolysaccharide in order to define a possible mechanism of the beneficial effects of HES. METHODS: Male Wistar rats were randomly divided into seven groups treated with saline, lipopolysaccharide (LPS, 6 mg/kg), LPS plus HES (3.75, 7.5, 15, 30 ml/kg), or HES (30 ml/kg) alone. Two hours after LPS challenge, NF-kappaB activation in the lungs, hearts, livers, and kidneys were examined with an electrophoretic mobility shift assay. Four hours after LPS challenge, plasma TNF-alpha concentrations were measured using an enzyme-linked immunosorbance assay. RESULTS: 3.75 and 7.5 ml/kg HES suppressed LPS-induced NF-kappaB activation in the four tissues and decreased plasma TNF-alpha elevation. The effects of 15 ml/kg HES was only significant in inhibiting NF-kappaB activity in the lung and liver. No effect of 30 ml/kg HES was revealed in all the cases. CONCLUSION: Lower doses of HES may inhibit tissue NF-kappaB activation and systemic TNF-alpha elevation after LPS challenge, which might be helpful during sepsis.

Animals↗
PubMed2005

Local anesthesia for functional endoscopic sinus surgery employing small volumes of epinephrine-containing solutions of lidocaine produces profound hypotension.

BACKGROUND: Local anesthetic containing epinephrine is commonly used in many operations for the main purpose of hemostasis. A randomized, controlled, prospective clinical trial was designed to find out hemodynamic changes after local infiltration of different concentrations and/or different dosages of epinephrine during functional endoscopic sinus surgery (FESS) under general anesthesia. METHODS: One hundred and eight adult patients undergoing elective FESS under general anesthesia were randomly allocated into four groups. Group I received 2% lidocaine 2 ml with epinephrine (5 microg/ml); group II received 1% lidocaine 4 ml with epinephrine (2.5 microg/ml); group III received 1% lidocaine 4 ml with epinephrine (5 microg/ml); and group IV received 1% lidocaine 4 ml for local infiltration. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) were monitored continuously in the radial artery and recorded in 6 min: before infiltration (baseline), 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, and 6 min after local infiltration. The lowest blood pressure (BP) in this period was also recorded. RESULTS: Significant hemodynamic changes, particularly a decrease in BP (P < 0.001) with a slight increase in HR (P < 0.001) at approximately 1.5 min and an increase in SBP at approximately 3 min (P < 0.01) after local infiltration, were observed in group I, group II and group III compared with the baseline, but not in group IV. No significant hemodynamic differences were observed between group I, group II and group III at the same time points (P > 0.05). CONCLUSION: Local infiltration of low-dose epinephrine causes temporary significant hemodynamic changes particularly a marked decrease in BP during FESS under general anesthesia.

Adolescent↗
PubMed2004

Ketamine inhibits LPS-induced calcium elevation and NF-kappa B activation in monocytes.

OBJECTIVE: To investigate whether ketamine could inhibit lipopolysaccharide (LPS)-induced intracellular calcium elevation and NF-kappa B activation in monocytes. MATERIALS AND METHODS: Isolated rat monocytes were challenged with 10 microg/ml LPS with or without the presence of various concentrations of ketamine (10, 100, 1000 microM). Intracellular calcium was monitored by laser confocal microscopy. NF-kappa B activity of the nuclear extracts of monocytes was analyzed by electrophoretic mobility shift assay (EMSA). RESULTS: LPS provoked a significant calcium elevation and enhanced NF-kappa B activity in monocytes. Ketamine above concentration of 100 microM inhibited endotoxin-induced intracellular calcium elevation and NF-kappa B activity. Ketamine itself had no effect on either of them. CONCLUSIONS: These findings suggest that ketamine could suppress NF-kappa B in monocytes exposed to endotoxin, and this anti-inflammatory effect might act through attenuating intracellular calcium elevation.

Animals↗
PubMed2004

Ketamine suppresses endotoxin-induced NF-kappaB activation and cytokines production in the intestine.

BACKGROUND: Ketamine has been advocated for anesthesia in endotoxemic and other severely ill patients because it is a cardiovascular stimulant. However, ketamine also suppresses serum levels of endotoxin-induced tumor necrosis factor-alpha, and reduces mortality in mice in endotoxin shock. Our study was designed to investigate the protective effect of ketamine on the endotoxin-induced proinflammatory cytokines and nuclear factor kappa B (NF-kappaB) activation in vivo. METHODS: Adult male Wistar rats were randomly divided into six groups: saline controls; rats challenged with endotoxin (5 mg kg(-1)) and treated with saline; challenged with endotoxin (5 mg kg(-1)) and treated with ketamine (0.5 mg kg(-1)); challenged with endotoxin (5 mg kg(-1)) and treated with ketamine (5 mg kg(-1)); challenged with endotoxin (5 mg kg(-1)) and treated with ketamine (50 mg kg(-1)); and saline injected and treated with ketamine (50 mg kg(-1)). TNF-alpha, IL-6 and NF-kappaB were investigated in the tissues of the intestine (jejunum) after 1, 4 and 6 h. RESULTS: Endotoxin caused transient production of TNF-alpha and IL-6 and activation of NF-kappaB in the intestine at peak times of 1, 4 and 1 h, respectively. Ketamine 0.5 mg kg(-1) suppressed endotoxin-induced TNF-alpha elevation and inhibited NF-kappaB activation in the intestine; a dose of 5 mg kg(-1) was required to inhibit IL-6. CONCLUSION: Ketamine suppresses the production of proinflammatory cytokines such as TNF-alpha and IL-6 in the intestine, possibly via inhibition of NF-kappaB.

Anesthetics, Dissociative↗
PubMed2001

Fluorescence immunoassay system based on the use of a pH-sensitive phase-separating polymer.

Poly(N-isopropylacrylamide-co-methacrylic acid) [P(NIPAAm-co-MAA)], a linear water-soluble pH-sensitive phase-separating polymer, was synthesized and used as a novel separation carrier for the reactants in immunoassay. This polymer precipitates out of water below a critical pH 5.8 at 37 degrees C and redissolves when the pH of solution is above 6.2. The characteristic of this polymer makes it possible to carry out the immunochemical steps of an immunoassay in a true solution and then to quickly separate the resulting product from the reaction mixture. The above approach was applied to determination of alpha-fetoprotein with the competitive immunoassay format. Compared with traditional ELISA using the same reactants, the proposed method was much faster (the assay time decreased from 100-120 to 30 min) and showed similar sensitivity, i.e., 0.04 ng/mL. In addition, a sandwich immunoassay method for the determination of hepatitis B surface antigen was also studied, and the results showed that the pH phase-separating immunoassay could be carried out through a sandwich or a competitive method. This general technique may also be used for a wide variety of separation processes in addition to immunoassay, in which a specific component is to be isolated for analysis, recovery, or disposal.

Acrylamides↗
PubMed2001

Phrenic nerve conduction study in patients with traumatic brachial plexus palsy.

Phrenic nerve conduction studies were performed to assess the ipsilateral nerve in 100 patients with traumatic brachial plexus palsy. Open exploration and intraoperative recordings of somatosensory evoked potentials and nerve action potentials were used to confirm the level of root lesions. The relationship between C-5 preganglionic root lesion and the functional integrity of the ipsilateral phrenic nerve was examined. The phrenic nerves were normal in 80 cases, partially injured in 7, and severely injured in 13. We found C-5 preganglionic root lesions in 13 (100%) patients with severely injured, 5 (71.4%) with partially injured, and 24 (30%) with normal phrenic nerves. This correlation suggests phrenic nerve conduction study is a useful tool in the diagnosis of C-5 preganglionic root lesions in patients with traumatic brachial plexopathy.

Adolescent↗
PubMed2001

Fluorescence immunoassay of alpha-fetoprotein with iron(III) tetrasulfonatophthalocyanine as a mimetic enzyme labeling reagent.

A new fluorimetric immunoassay for alpha-fetoprotein (AFP) has been developed using a novel promising mimetic peroxidase, iron(III) tetrasulfonatophthalocyanine (FeTSPc), as a labeling reagent to catalyze the fluorescence reaction of P- hydroxyphenylacetic acid (P-HPA) and hydrogen peroxide (H2O2). In the competitive immunoassay, anti-AFP antibody was coated on a 96-well plate (polystyrene) and a constant amount of FeTSPc-labeled AFP and a known amount of test solution were added. Non-labeled and FeTSPc-labeled AFP compete for binding to the plate-bound antibody. After the immunoreaction, the immunochemically adsorbed FeTSPc-AFP conjugate moiety was determined by measuring the fluorescence produced in a solution containing P-HPA and H2O2. AFP can be determined in the concentration range of 1-300 ng mL(-1) with a detection limit of 0.5 ng mL(-1).

Antibodies↗
PubMed2001

Determination of nucleic acids based on shifting the association equilibrium between tetrasulfonated aluminium phthalocyanine and acridine orange.

Based on the ability of nucleic acids to shift the association equilibrium of the ion-association complex of Acridine Orange and tetrasulfonated aluminium phthalocyanine, thus leading to an increase in the phthalocyanine fluorescence, a method is suggested for the fluorimetric determination of nucleic acids. Investigations were carried out on the spectral characteristics, order of addition of reagents, selection of the buffer system, effect of pH, influence of reaction time, effect of salt, the usage of reagents, interference of foreign substances and the effect of different acridine derivatives. Under the optimum conditions, the calibration graphs for the determination of calf thymus DNA (CT DNA), salmon DNA (SM DNA) and yeast RNA were linear over the ranges 0.04-1.2, 0.04-1.2 and 0.1-1.2 micrograms cm-1, respectively. The detection limits for CT DNA, SM DNA and RNA were 17, 24 and 98 micrograms cm-3, respectively. The relative standard deviation (n = 6) was within 4.6% for the detection of samples. The method was applied to the determination of Staphylococcus aureus DNA and the result was in agreement with that achieved by a UV method.

Acridine Orange↗
PubMed2001

A new red-region substrate, tetra-substituted amino aluminium phthalocyanine, for the fluorimetric determination of H2O2 catalyzed by mimetic peroxidases.

A new red-region fluorogenic substrate, tetra-substituted amino aluminium pthalocyanine, was developed for the selective determination of H2O2 based on the catalytic effect of mimetic peroxidases, viz., hemin or iron tetrasulfonatophthalocyanine (FeTSPc). Under the optimum conditions, the linearity of the calibration graph for the determination of H2O2 with hemin (or FeTSPc) as the catalyst was in the range from 0.0 to 3.0 x 10(-7) mol L-1 (or from 0.0 to 2.0 x 10(-6) mol L-1). The detection limits were 3.7 x 10(-9) and 4.9 x 10(-9) mol L-1 H2O2, respectively. The relative standard deviation (n = 7) was within 1.5% in the middle of the linear range. The peroxidase activity of the mimetic enzymes hemin and FeTSPc, the effects of some experimental conditions and the influence of foreign substances were investigated. With this substrate, 0.0-7.5 x 10(-8) mol L-1 hemin and 0.0-2.0 x 10(-6) mol L-1 FeTSPc can be determined with an accuracy and precision of about 1.3%. The potential application of the reagent was tested by the determination of H2O2 in rainwater.

Hemin↗
PubMed2001

Naloxone increases vascular responsiveness in chronic morphine treated rats and facilitates intracellular signaling in cultured vascular cells.

AIM: To probe the changes of vascular responsiveness and intracellular signaling during opiate withdrawal syndrome. METHODS: Morphine withdrawal syndrome in rats was precipitated by iv naloxone following daily injection of increasing dose of morphine for 2 weeks, the changes in mean arterial blood pressure (MBP) caused by acetylcholine (ACh) were recorded. Isolated mesenteric vascular beds were perfused with Kreb's solution containing different concentration of drugs. The cytoplasmic Ca2+ ([Ca2+]i) in Fura 2-loaded cultured bovine aortic endothelial cells (aec) and smooth muscle cells (smc) were assayed. The positive immunoreaction to the phosphorylated cyclic AMP responsive element-binding protein (phospho-CREB) in cultured smc was calculated. RESULTS: Naloxone 2 mg/kg iv following chronic morphine treatment precipitated severe opiate withdrawal signs in company with blunted hypotensive effect of Ach that was the same as chronic morphine treated rats before withdrawal. In the mesenteric vascular beds from chronic morphine treated rats, the EC50 of pressor effect of norepinephrine (NE) was decreased from (2.06 +/- 0.38) to (1.14 +/- 0.21) micromol/L (n = 8, P < 0.01) after the perfusion solution containing morphine 20 micromol/L was replaced by Kreb's containing naloxone 25 micromol/L. Furthermore, NE-induced perfusion pressure increases were completely prevented by Kreb's contained morphine 40 micromol/L. Morphine acutely applied to control smc produced some variable and naloxone-reversible [Ca2+]i changes, but naloxone did not. However, naloxone increased [Ca2+]i in two thirds of smc preincubated with morphine 0.1 or 0.5 mmol/L for 48 h from (97 +/- 20) to (167 +/- 29) nmol/L (n = 9, P < 0.01) and from (106 +/- 19) to (225 +/- 48) nmol/L (n = 10, P < 0.01), respectively, and it also increased the ratio of positive immunoreaction to phospho-CREB from (7.7 +/- 3.2) % to (19.6 +/- 4.7) % (n = 6, P < 0.01) in smc preincubated with morphine 0.5 mmol/L. In addition, naloxone decreased [Ca2+]i from (146 +/- 34) to (78 +/- 24) nmol/L in one third morphine-preincubated aec (n = 10, P < 0.01). CONCLUSION: That naloxone enhances vascular responsiveness to NE in chronic morphine treatment rats may be relevant to [Ca2+]i transient facilitation in company with cAMP-dependent phosphorylation enhancement.

Animals↗
PubMed2001

[Culture of human muscle satellite cell].

OBJECTIVE: To investigate the biological characteristics of human muscle satellite cell cultured in vitro. METHODS: Human muscle satellite cells were obtained from skeletal muscle biopsies of six patients during corrective orthopedic surgery, cultivated in growth medium for ten days, then in differentiation medium for additional five days. Human satellite cells were identified with monoclonal antibody against desmin. Cells were observed under phase contrast microscopy. RESULTS: Human muscle satellite cells proliferated in growth medium, and fused to form myotubes in differentiation medium. After 24 hours in differentiation medium, the confluent satellite cells began to fuse actively and achieved the top level at 72 hours. CONCLUSION: Human muscle satellite cell can proliferate and differentiate in appropriate culture condition. Immunocytochemical detection of desmin is the effective early method to determine satellite cell.

Adolescent↗
PubMed2000

A novel method for the determination of total protein in human serum by near infrared fluorescence recovery.

A novel fluorometric method has been developed for the determination of total protein in human serum with a new near-IR reagent as a fluorescence probe, based on the fluorescence recovery of the cyanine-CTAB system in the presence of protein. Maximum fluorescence is produced with maximum excitation and emission wave-lengths at 765 and 812 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.4-12.0 microg/mL for protein. The detection limit is 70 ng/mL, and the relative standard deviation of six replicate measurements is 1.14% for 6.0 microg/mL protein. The results are satisfactory.

Animals↗
PubMed2000

Application of magdala red as a fluorescence probe in the determination of nucleic acids.

A fluorescence quenching method was developed for the rapid determination of DNA and RNA using magdala red as fluorescence probe. In weakly acidic medium, the fluorescence of magdala red (lambdaex/lambdaem = 540/555 nm) can be largely quenched by DNA or RNA. The calibration graphs are linear over the range 0.01-1.2 microg/mL for both calf thymus DNA (CT DNA) and salmon DNA (SM DNA), and 0.015-1.0 microg/mL for yeast RNA, respectively. The corresponding detection limits are 6.0 ng/mL for CT DNA, 7.0 ng/mL for SM DNA and 15.0 ng/mL for yeast RNA, respectively. CT DNA could be determined in the presence of 20% (w/w) yeast RNA, and the relative standard deviation of six replicate measurements is 3.18% for 400 ng/mL of CT DNA. Interference from coexisting substances in the determination of DNA was also examined. Real samples were determined with satisfactory results.

Adenine↗
PubMed2000

Cationic cyanine as a near-infrared fluorescent probe for the determination of nucleic acids.

A new method with a cationic near-IR cyanine as fluorescent probe was developed for the determination of nucleic acids. The near-IR cyanine shows maximum excitation and emission wavelengths at 765 and 790 nm, respectively, in aqueous solution. The method is based on the fluorescence decrease of near-IR cyanine in the presence of nucleic acids. Under optimal conditions, the ratio of fluorescence intensity in the absence and presence of nucleic acids was proportional to the concentration of nucleic acids over the range 0.10-1.2 microg/mL for CT (calf thymus) DNA or SM (salmon sperm) DNA, and 0.10-1.6 microg/mL for yeast RNA. The detection limits were 30 ng/mL for CT DNA, 25 ng/mL for SM DNA and 70 ng/mL for yeast RNA. The relative standard deviation (n = 6) was 2.1% for 500 ng/mL CT DNA, 2.4% for 500 ng/mL SM DNA and 2.7% for 500 ng/mL yeast RNA, respectively.

Carbocyanines↗