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Biomedical subjects

A Luo

Publications and source records attributed to A Luo.

At least 19 recordsLinked to original sources
PubMed2003

Intraoperative catecholamine release in brain-dead organ donors is not suppressed by administration of fentanyl.

BACKGROUND AND OBJECTIVE: Endogenous catecholamines are released in brain-dead organ donors following painful stimulation during retrieval surgery, and might be harmful to harvested organs. Our hypothesis was that inhibition of pain by fentanyl would inhibit such catecholamine release. METHODS: We tested 17 brain-dead organ donors in a randomized, placebo-controlled, double-blinded study. Blood samples for determination of epinephrine and norepinephrine concentrations were obtained before and 10 min after in take of either fentanyl 7 microg kg(-1) or an equivalent volume of placebo. Further points of measurement were taken after skin incision and sternotomy. Mean arterial pressure and heart rate at these points were recorded. RESULTS: Catecholamine concentrations rose following painful stimuli. No differences in haemodynamics, between the fentanyl and the placebo group were detectable. Epinephrine concentrations, but not those of norepinephrine, were higher in the fentanyl group, reaching significance following sternotomy. CONCLUSION: We conclude that the use of fentanyl (7 microg kg(-1)) was not effective in suppressing the catecholamine release, following painful surgical stimulation in brain-dead organ donors.

Adult↗
PubMed2003

Effects of bioreactor temperature and time on odor-related parameters in aerated swine manure slurries.

Previous studies have linked odor generation from swine manure to some characteristics of the liquid manure such oxidation-reduction potential (ORP), five-day biochemical oxygen demand (BOD5), volatile fatty acids (VFAs), and predominant microbial population. This study investigated the effect of bioreactor temperature and time on the aforementioned parameters during aeration of swine manure. Five reactors (13 1 capacity) loaded with swine manure and maintained at temperatures of 5, 10, 15, 20, and 25 degrees C, were supplied with air for 15 days to maintain aerobic conditions. Large fluctuations in ORP (-120 to 360 mV) were observed in the first seven days of aeration, which stabilized thereafter regardless of the bioreactor temperature. The percentage removal of VFAs and BOD5 in the manure significantly increased from 0.0% on day one to 87.8% and 65.3%, respectively, on day nine, and remained relatively constant thereafter. The mean percentage of VFAs and BOD5 removed also increased significantly with an increase in the bioreactor temperature. The VFAs and BOD5 removal increased by approximately 25% and 35%, respectively, in going from 5 to 25 degrees C, during the 15 days of aeration. Both VFAs and BOD5 in the manure were significantly correlated with ORP, aerobic bacteria, and anaerobic bacteria. The data suggested that continued aeration for seven days at 20 or 25 degrees C was sufficient for significant reduction of odor precursors (VFAs and BOD5) and in stabilization of swine manure. A linear correlation of 0.97 between VFAs and BOD5 indicated that the two parameters can be used interchangeably as indicators of odor release potential in swine manure.

Air Pollutants↗
PubMed2001

Effect of solid-liquid separation on BOD and VFA in swine manure.

Fresh swine manure was sieved into seven different particle size categories, i.e., <0.075 mm, < 0.15 mm, < 0.25 mm, < 0.5 min, < 1.0 mm, < 1.4 mm, and < 2.0 mm. Manure was stored in seven PVC columns and sampled every 5 days up to 30 days. Manure samples were analyzed for total volatile fatty acids (VFAs), 5-day biochemical oxygen demand (BOD5), total solids (TS), total suspended solids (TSS), and total volatile solids (TVS). Two parameters (VFAs and BOD5) were used to determine the odor generation potential of the test manure. The results showed that total VFAs correlated well with BOD5 (R2 = 0.8297). The levels of ISS only explained 40% of BOD5 and 46% of VFAs, both of which increased with storage time, regardless of solid particle sizes. Also, the data inferred that most of the odorous compounds (measured by VFA and BOD levels) were contained in manure solid particles less than 0.075 mm. These cannot be removed by commercial mechanical separators with screen size ranging from 0.5 to 3.0 mm. With an average separation efficiency of 25% for most commercially available mechanical separators, the removal efficiencies of BOD5 and VFAs were as low as 10% and 12%, respectively. These findings cannot justify the use of solid-liquid separation tocontrol odor. Data also showed that for swine manure, it is critical to run separation treatment within the first ten days after the manure is excreted to potentially improve the separation efficiency. After ten days, the degradation of TSS was accelerated due to the increased biological activities, which may greatly reduce the separation efficiency.

Animals↗
PubMed2001

The effect of limited aeration on swine manure phosphorus removal.

Two low level aeration schemes (intermittent vs. continuous) were investigated on a laboratory scale, in conjunction with swine manure pH adjustment using sodium hydroxide (1.0 M), for manure phosphorus (P) removal. According to the data, an 80% reduction in soluble P was observed when the manure pH was increased to 8. Both intermittent and continuous aeration treatments could raise manure pH above 8 with an airflow rate of 1 L/minute in a period of 15 days. A drastic increase in pH (about 1 unit) was observed for both aeration schemes within the first day of test, resulting in a 76% reduction in soluble P concentration in the liquid. It appeared that there is no difference in terms of P removal between the two aeration programs, suggesting that the intermittent aeration be preferred to save energy while still achieving the same level of P removal.

Air↗
PubMed2001

[Automatic detecting 400.0 nm break of galaxies spectra].

This paper presents an automatic method to detect the position of 400.0 nm break in galaxies spectra. This spectral discontinuity is due to the opacity produced by the presence of a large number of spectral lines of ionized metal. It is largely used to determine the star formation characteristics of distant field and cluster galaxies. The position of the discontinuity is an indicator of redshift. Detecting the position by hand is not possible in a sky survey with large amount of spectra data. We develop an automatic method using wavelet transform and discrete convoution. All steps are given in the paper. The program subtracts the spectral lines from a continuum using wavelet filter and determines that the spectrum is an emission line galaxy. Then the discontinuity position is obtained by convolution between a step function and the continuum, at last, the program computes the redshift z, and identifies strong emission lines using computed z. When the strong lines are identified, the position is determined. We use 3 data set to test our program. The results suffice to show that discontinuity position is very precisely measured. This method can be the first step for studying the galaxies spectra surveys.

English Abstract↗
PubMed2000

Effect of cardiopulmonary bypass on beta adrenergic receptor-adenylate cyclase system on surfaces of peripheral lymphocytes.

The experimental results showed that the level of CAMP, the ratio of cAPM to cGMP, IL-2R expression and IL-2 production in vitro in lymphocytes immediate and 2 weeks after cardiopulmonary bypass (CPB) were significantly lower than those before anesthetics in the patients undergoing cardiac surgery with CPB. These findings suggested that CPB could cause serious damage to adrenergic beta receptor-adenylate cyclase system on circulating lymphocytes surfaces, which might be one of the mechanisms resulting in immunosuppression after open heart surgery with CPB.

Adenylyl Cyclases↗
PubMed2000

Propofol combined with diazepam synergistically potentiates the GABA-activated chloride current in rat sensory neurons.

OBJECTIVE: To investigate the effect of propofol combined with diazepam on the gamma-aminobutyric acid (GABA)-activated chloride current (IGABA) evoked in rat sensory neurons. METHODS: Whole cell patch clamp recordings were made from cultured rat dorsal root ganglionic neurons. GABA (3 mumol/L) was applied by pressure ejection. The anesthetics were dissolved in the external solution and given by the "Y-tube" method. RESULTS: Co-application of propofol (0.3-3 mumol/L) and diazepam (100 nmol/L) potentiated the IGABA which was significantly larger than the sum of that potentiated by drug alone. Diazepam (100 nmol/L) shifted the concentration-response curve for the IGABA potentiation induced by propofol to the left in a parallel fashion. The EC50 value for propofol was decreased by diazepam from 7.6 +/- 1.8 mumol/L to 3.9 +/- 1.1 mumol/L (n = 9). CONCLUSIONS: Our results suggest that propofol combined with diazepam synergistically potentiates the IGABA. Diazepam-induced increase in the apparent binding affinity of propofol for the GABAA receptors is likely responsible for a clinical synergistic hypnotic action during co-application with propofol and diazepam.

Animals↗
PubMed2000

[The effects of sodium nitroprusside-induced hypotension at different levels on cerebral blood flow and metabolism: a clinical study].

OBJECTIVE: The clinical experiment was designed for observing the effects of deliberate hypotension at different level on cerebral blood flow and metabolism. METHODS: 30 ASA Grade I-II patients were randomly allocated to one of three groups (each group n = 10). Hypotension was induced by sodium nitroprusside in group 1[mean arterial pressure (MAP) = 55 mmHg] and group 2 (MAP = 65 mmHg). Group 3 (control) was on normotension. The changes of cerebral blood flow during hypotension were estimated according to the variability of cerebral blood flow velocity (CBFV) in the middle cerebral artery(MCA), which was obtained through transcranial Doppler ultrasonography (TCD). RESULTS: Hypotension caused a moderate decrease in CBFV, but no significant difference, in CBFV and oxygen saturation in internal jugular vein(SjO2), either among three groups or during the procedure. CONCLUSIONS: It is safe for cerebral perfusion and metabolism with deliberate hypotension at MAP = 55 mmHg.

Antihypertensive Agents↗
PubMed2000

[Effect of propofol and etomidate for anesthesia induction on plasma total cortisol concentration].

OBJECTIVE: To investigate the effect of propofol and etomidate for anesthesia induction on adrenocortical function. METHODS: The plasma total cortisol concentration was determined in 20 patients who were treated with propofol or etomidate. RESULTS: After propofol induction, the plasma total cortisol level decreased from (308.7 +/- 27.4) nmol/L to (267.7 +/- 31.2) nmol/L at post-medication 2 hours, increased to (400.2 +/- 26.9) nmol/L at postmedication 5 hours and restored to premedication level at postmedication 24 hours [(306.4 +/- 35.4) nmol/L]. After etomidate induction, the plasma total cortisol level decreased from (309.1 +/- 36.6) nmol/L to (115.9 +/- 29.7) nmol/L at postmedication 2 hours, maintained (171.1 +/- 34.7) nmol/L at postmedication 5 hours and restored to premedication level at postmedication 24 hours [(311.8 +/- 46.2) nmol/L]. CONCLUSIONS: Propofol induction has little effect on adrenocortical function whereas etomidate induction inhibits adrenocortical function.

Adrenal Cortex↗
PubMed1999

[Bolus administration of esmolol for preventing the haemodynamic response to tracheal intubation: a multicentre clinical study].

OBJECTIVE: To explore the dose-response relation and the safety of esmolol administered as a single i.v. bolus prior to the induction of anesthesia for preventing the haemodynamic response to tracheal intubation. METHODS: 1,830 patients from 20 centres were randomly divided into three groups: E1 group, receiving esmolol at a dose of 1 mg/kg; E2 group, at 2 mg/kg and E0 group, receiving 0.9% NaCl. Heart rate, systolic and diastolic, and mean artery blood pressures (MAP) were measured following the induction and 1 to 10 minutes following the intubation. RESULTS: The patients in the E0 group had greater HR and MAP values after anesthesia induction and tracheal intubation than the patients in the E1 and E2 groups (P < 0.05-0.01). The E1 group had higher HR than the E2 group (P < 0.05-0.01). The incidence of tachycardia after intubation was higher in the E0 group (63.8%) than in the E1 group (34.7%) and the E2 group (22.6%) (P < 0.01). The proportion of hypotention and bradycardia was higher in the two treatment groups than the E0 group (P < 0.01), but no severe adverse event was observed. CONCLUSION: A 1-2 mg/kg bolus of esmolol is effective and safe for preventing the haemodynamic response to tracheal intubation. The clinical and side-effects are all dose-related.

Adolescent↗
PubMed1999

Additive potentiation by co-application of propofol and sevoflurane on GABA-induced chloride current in cultured neurons from rat dorsal root ganglia.

OBJECTIVE: To investigate the effects of various concentrations of sevoflurane and propofol and a combination of the two agents on chloride current induced by bath utilization of 3 x 10(-6) mol/L gamma-aminobutyric acid (GABA) in the rat dorsal root ganglia neurons maintained in primary culture. METHODS: Sensory neurons from rat dorsal root ganglia were dissociated and cultured. The whole-cell patch clamp technique was used to record chloride current. All drugs were applied with a rapid perfusion system, named "Y-tube" method. RESULTS: The peak chloride current amplitude was induced by 3 x 10(-6) mol/L GABA with substantially increasing of both sevoflurane and propofol. Additionally, desensitization of IGABA induced by either propofol or sevoflurane was not observed. We examined actions of various concentrations of propofol (3 x 10(-7), 1 x 10(-6), 3 x 10(-6) mol/L), sevoflurane (7 x 10(-4) mol/L) and their combination at concentrations relevant to clinical anesthesia on IGABA propofol (3 x 10(-7), 1 x 10(-6), 3 x 10(-6) mol/L) produced a concentration-dependent increase in the response to 3 x 10(-6) mol/L GABA on IGABA. When combined with 7 x 10(-4) mol/L sevoflurane, the potentiation of response to GABA obtained with various concentrations of propofol was not different from a theoretical additive response (P > 0.05). CONCLUSIONS: Either sevoflurane or propofol and their combination at clinically relevant concentrations potentiate the GABA-induced chloride current, which may at least partially contribute to the anesthetic mechanism. Additive interaction obtained with a co-application of propofol and sevoflurane may provide an evidence for a clinical combination of these two anesthetic agents.

Anesthetics, Inhalation↗
PubMed1999

Effects of alfentanil and esmolol on hemodynamic and catecholamine response to tracheal intubation.

OBJECTIVE: To compare the effects of alfentanil and esmolol on hemodynamic and catecholamine response to tracheal intubation. METHODS: Thirty-five adult patients were randomly allocated to one of three groups, Group A (control group). Group B (esmolol group) and Group C (alfentanil group). The patients received either 2 mg/kg esmolol (in Group B) or 30 microg/kg alfentanil (in Group C) before intubation. Tracheal intubation was performed with 4 mg/kg thiopental and 0.1 mg/kg vecuronium and 3% isoflurane. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), heart rate (HR), norepinephrine (NE), epinephrine (E) and dopamine (DA) were measured before and after intubation. RESULTS: The control group had a baseline SBP of 149 +/- 23 mmHg while Groups B, C had a baseline SBP of 148 +/- 23, and 150 +/- 21 mmHg, respectively (P>0.05). Three min after tracheal intubation, the control group SBP increased to 160 +/- 30 mmHg and Group B remained at the baseline level, 147 +/- 5 mmHg, and Group C significantly decreased to 91 +/- 22 mmHg (P<0.01). Two min after intubation HR in Group B increased significantly but 3 min after intubation HR in Groups B and C were significantly lower than that of control group (P<0.05). NE in Groups A and B increased significantly to 5.75 +/- 3.51 and 6.75 +/- 3.30 nmol/L 3 min after intubation (P<0.01). In Group C, 3 min after intubation NE was not significantly different from the baseline but E decreased significantly (P<0.01). CONCLUSION: 2 mg/kg esmolol can moderate the hemodynamic response to tracheal intubation to a certain extent and 30 microg/kg alfentanil can completely attenuate the hemodynamic and catecholamine responses.

Adrenergic beta-Antagonists↗
PubMed1998

[The protective effect of captopril during myocardial ischemia and reperfusion and its mechanism].

OBJECTIVE: To investigate the myocardial protective effect of captopril (Cpl) during ischemia and reperfusion injury. METHODS: Sixteen mongrel dogs were randomly divided into the control and Cpl groups. In the control group, only modified St. Thomas cardioplegia was used. In the Cpl group, St. Thomas cardioplegia and reperfusional blood containing captopril 4.6 mumol/L were used. The plasma renin activity (RA), contents of angiotensin II (AT-II) and endothelin-1 (ET-1) in arterial blood were determined before cardiopulmonary bypass (CPB) and 5, 35, 60 min after reperfusion. The myocardial RA, contents of AT-II, ET-1 and malondyldialdehyde (MDA) were also measured. Parameters of cardiac function were monitored simultaneously. RESULTS: In the control group the plasma RA, AT-II and ET-1 contents were increased after reperfusion and significantly higher than those before CPB (P < 0.01). However, the content of AT-II in the Cpl group was not increased after reperfusion. The content of ET-1 in the Cpl group was increased but significantly lower than that in the control group (P < 0.01). The myocardial AT-II, ET-1 and MDA contents in the Cpl group were significantly lower than those in the control group. The cardiac index (CI) and coronary blood flow (CBF) in the Cpl group regained normal after reperfusion at 35 min. CONCLUSIONS: Cardioplegia and reperfusion blood containing 4.6 mumol/L captopril could ameliorate the cardiac performances by inhibiting myocardial and systemic RAS and decreasing the ET-1 production.

Angiotensin II↗
PubMed1998

[Simultaneously monitoring end tidal CO2 and other parameters versus anesthesia management].

OBJECTIVE: To investigate the significance of end tidal CO2(ETCO2) combined with other techniques in anesthesia management. METHODS: Twenty two patients undergoing general anesthesia were monitored with electromyocardiogram (ECG), invasive arterial blood pressure (IABP), plethysmogram and capnography simultaneously. Ten patients undergoing epidural anesthesia and cervical plexus block were monitored with ETCO2. RESULTS: During general anesthesia the depth of general anesthesia, status of ventilation and the degree of muscle relaxation could be grossly evaluated by simultaneously monitoring ETCO2, capnography, plethysmogram, ECG and IABP. ETCO2 could also provide an objective standard for the assessment of respiratory function during spontaneous ventilation. CONCLUSIONS: ETCO2 combined with other monitoring techniques can increase the safety of anesthesia and the accuracy of anesthesia management.

Anesthesia, Epidural↗
PubMed1998

[Biological responses of a Streptomyces strain producing-Nikkomycin to space flight].

In order to see biological responses to the production of Nikkomycins in general and Nikkomycin X and Z in particular by space conditions, Streptomyces ansochromogenus, a Nikkomycins-producing strain, was carried onboard a satellite for 15 d in 1996. Several strains were isolated from the treated sample and found that the productivity of Nikkomycins in all was increased by 13-18 percent, and the proportion of Nikkomycin X and Z increased correspondingly. Besides, some biological properties of the isolated strains varied markedly.

Aminoglycosides↗
PubMed1998

The change of arteriovenous carbon dioxide and pH gradients during severe hemorrhagic shock and resuscitation.

OBJECTIVE: To investigate clinically useful markers for determining the severity of hemorrhagic shock and adequacy of resuscitation. METHODS: Prospective study was undertaken in 12 dogs, using an established model for hemorrhagic shock. The anesthetized dogs were bled to a mean arterial pressure of 40 mmHg which was maintained for 3 hours. Then each animal was resuscitated with heperinized whole blood followed by intravenous infusion of dobutamine at a rate of 5 micrograms.kg-1.min-1 for 10 minutes. Arterial and mixed venous blood gases, arterial lactate concentrations and hemodynamic parameters were measured throughout the study. RESULTS: A difference in the PCO2 and pH values between arterial and mixed venous blood was observed. Arterial-venous PCO2 and pH difference increased significantly after sustained shock. The arteriovenous carbon dioxide and pH gradients recovered more rapidly than arterial lactate levels after successful resuscitation with blood and dobutamine. CONCLUSION: Arterial blood gases fail to reflect the acid-base status of tissues during hemorrhagic shock. The differences in PCO2 and pH values between arterial and mixed venous blood could be used as clinical indicators for assessing the severity of shock and efficacy of resuscitation.

Animals↗
PubMed1997

[Effects of captopril on the myocardial performances and hemodynamics after cardiac arrest].

UNLABELLED: The effects of cardioplegia and reperfusional blood containing 4.6 mumol/L captopril (CPL) on the myocardial performances and hemodynamics of canine heart under hypothermic extracorporeal circulation were studied. Twenty four mongrel dogs were divided randomly into 3 groups. CONTROL GROUP: Only modified St. Thomas cardioplegia was used. CPL group: St. Thomas cardioplegia containing CPL 4.6 mumol/L was used and the same concentration of captopril in the circulatory blood was established before releasing the cross clamp. CPL + phenylephrine group: The concentration was the same as the CPL group, with an additional dose of phenylephrine (2 micrograms/kg) into the oxygenator and abdominal coarctation. The results revealed that the coronary blood flow and left ventricular contractility and relaxation indices of CPL group were significantly improved than those of the control group, and increasing the systemic and pulmonary vascular resistence had no effect on the cardiac function protected by captopril. It is suggested that captopril could ameliorate the recovery of myocardial performences by inhibitting myocardial and systemic renin-angiotensin system and scavenging free radicals.

Angiotensin-Converting Enzyme Inhibitors↗