PubMed Health⌕ Search

Biomedical subjects

C C Shu

Publications and source records attributed to C C Shu.

14 recordsLinked to original sources
PubMed1998

Effect of active and passive cigarette smoking on CYP1A2-mediated phenacetin disposition in Chinese subjects.

The effect of active and passive cigarette smoking on CYP1A2-mediated phenacetin disposition was evaluated in a controlled study of 36 healthy Chinese subjects. Each subject was administered a single oral dose of phenacetin (900 mg), and frequent blood samples were taken for up to 12 hours for simultaneous high-pressure liquid chromatography determinations of plasma concentrations of phenacetin and metabolically derived paracetamol. Compared with values observed in controls not exposed to cigarette smoking, subjects who smoked 7 to 40 (median, 20) cigarettes per day exhibited a 2.5-fold higher phenacetin apparent oral clearance (7.2, 4.3-12.0 L x h(-1) x kg(-1) vs 2.9, 1.8-4.6 L x h(-1) x kg(-1) [geometric means, 95% confidence intervals]; n = 12, p < 0.05). In subjects exposed to passive smoking, phenacetin's apparent oral clearance (3.6, 2.0-46.6 L x h(-1) x kg(-1), n = 12) was intermediate between the values observed in the two other groups. Plasma paracetamol levels were moderately lower in active smokers than in passive smokers and controls. These results demonstrated that, in contrast to results found in previous studies, Chinese subjects were fully susceptible to the inducing effect of cigarette smoke on CYP1A2 activity.

Adult↗
PubMed1996

Comparison of diuretic effects of glycerol with furosemide after transurethral prostatectomy.

BACKGROUND: Diuretic therapy after transurethral prostatectomy (TURP) is primarily intended to induce diuresis against water intoxication and cystic clot retention. This study was undertaken to compare the diuretic effects of glycerol with furosemide after TURP. METHODS: Thirty patients (ASA I or II) undergoing TURP were studied. Spinal anesthesia was induced with bupivacaine. At the end of prostatic resection, the patients were randomly allocated into two groups. In one group (n = 15) the patients received furosemide 30 mg i.v., while in the other group (n = 15) they received glycerol 0.5 g/kg i.v. Blood samples were collected for measurements of osmolality, hematocrit, sodium and glucose concentration before anesthesia and after surgery. Urine output was also recorded after surgery in each group. RESULTS: Plasma osmolality in glycerol group was higher than furosemide group at 30 min (295.3 +/- 10.6 vs. 283.8 +/- 5.6 mOsm/kg, p < 0.01) and 1 h after operation (294.9 +/- 8.7 vs 286.3 +/- 6.7 mOsm/kg, p < 0.01). Blood glucose was higher in glycerol group than that in furosemide group at 2 h after operation (195.6 +/- 121.9 vs 152.9 +/- 70.1 mg/dl, p < 0.05). Measured urine output was significantly greater in furosemide group at 30 min after operation (904.6 +/- 491.5 vs. 248.4 +/- 143.4 ml, p < 0.05) but was greater in glycerol group at 12 h after operation. CONCLUSIONS: Since urine output is significantly less in glycerol group at 1 h after operation, glycerol is inferior to furosemide for preventing cystic clot retention after TURP. But glycerol may protect against water intoxication better for its merit of producing higher plasma osmolality.

Aged↗
PubMed1995

Magnesium sulfate has negligible effect on middle cerebral artery blood flow velocity in response to endotracheal intubation.

BACKGROUND: Pretreatment of magnesium sulfate (MgSO4) attenuates pressor response associated with endotracheal intubation. Vasodilating effect of MgSO4 may increase cerebral blood flow, which upsets the known benefit to cardiovascular hemodynamic. In the present study, we evaluated the effect of MgSO4 on the changes of cerebral blood flow in response to endotracheal intubation. METHODS: Twenty four ASA class I or II patients who randomly received either normal saline 5 ml or MgSO4 (60 mg/kg, i.v.) 3 min before induction of anesthesia were included in the study. Mean blood flow velocity (VMCA) of the middle cerebral artery was obtained using a transcranial Doppler sonography (TCD) before and after endotracheal intubation. Anesthesia was induced with fentanyl (4 micrograms/kg) and thiopental (5 mg/kg) and endotracheal intubation was facilitated with succinylcholine (1.5 mg/kg). RESULTS: Before endotracheal intubation, MgSO4 caused a transient decrease in VMCA (98 +/- 6% vs. 76 +/- 3% of baseline) and increase in heart rate (132% vs. 114% of baseline) compared to saline group. However, VMCA and heart rate did not show significant difference in both groups after tracheal intubation. Also, systolic and diastolic blood pressure did not differ during the study. CONCLUSIONS: Our results suggest that MgSO4 appeared to have negligible effects on cerebral blood flow and hemodynamics in response to tracheal intubation. Its attenuating effect on pressor response induced by endotracheal intubation might be over emphasized.

Adult↗
PubMed1995

A protective role for glutathione-dependent reduction of dehydroascorbic acid in lens epithelium.

PURPOSE: In view of the antioxidant role of ascorbic acid and the glutathione redox cycle in the lens, the authors have studied the relationship of the cycle to reduction of the oxidized product of ascorbic acid, dehydroascorbic acid (DHA), in lens epithelium. METHODS: Cultured dog lens epithelial cells and intact rabbit lenses were exposed to various concentrations of DHA in experiments performed at 20 degrees C to minimize hydrolysis of the compound (t1/2 of 5 minutes at 37 degrees C). Levels of glutathione (GSH) and oxidized glutathione (GSSG) were measured in lens cells and whole lens epithelial by electrochemical detection. RESULTS: Treatment of lens cells with 1 mM DHA for 0.5 to 3 hours in the absence of glucose (glucose is required for the reduction of GSSG through the glutathione redox cycle) produced from 60% to complete oxidation of GSH (controls contained negligible GSSG) and distinct morphologic changes (cell contraction and blebbing), as shown by scanning electron microscopy. Glucose prevented these effects and allowed nearly immediate recovery of GSH after DHA exposure in the absence of glucose. A dose-dependent response was observed for the formation of GSSG in cultured cells from 0.05 to 0.5 mM DHA in the absence of glucose. The results of experiments performed with DHA plus an inhibitor of glutathione reductase mimicked those obtained using DHA minus glucose. DHA produced a 3- to 10-fold stimulation of hexose monophosphate shunt activity in cultured lens cells and whole lenses, which was prevented by the inhibition of glutathione reductase. Treatment of whole lenses with DHA minus glucose also produced oxidation of epithelial GSH and was accompanied by the loss of lens transparency. No evidence was found for dehydroascorbate reductase activity in the lens epithelium. CONCLUSIONS: The exposure of lenses and lens epithelial cells to DHA under conditions in which the glutathione redox cycle was compromised resulted in the disappearance of GSH in the tissues and the appearance of GSSG. The reduction of DHA was shown to be linked to the glutathione redox cycle by a nonenzymatic interaction between GSH and DHA. Reduction of DHA in the lens is important because of the potential toxicity of this oxidant and/or its degradation products.

Animals↗
PubMed1995

Mannitol increases cerebral arteriovenous oxygen difference in patients undergoing craniotomy.

BACKGROUND: Monitoring the jugular venous oxygen saturation (SjVO2) and cerebral arteriovenous oxygen difference (AVDO2) is valuable in detecting cerebral ischemia. In the present study, we investigated the effect of mannitol on SjVO2 and AVDO2 in patients undergoing craniotomy. METHODS: We studied 25 ASA class II-III patients undergoing craniotomy. Anesthesia was induced with thiopental, fentanyl and vecuronium. Immediately after induction, a 16-gauge central venous catheter was placed in the internal jugular vein, ipsilateral to the lesion side with cephalic insertion and anchorage in the jugular bulb. Anesthesia was maintained with continuous infusion of fentanyl (10 micrograms/kg/h), 0.5-1% isoflurane in 60% oxygen (oxygen/air) and supplemental dose of vecuronium for muscle relaxation as needed. Samples of arterial and jugular venous blood were obtained for the measurements of SjVO2 and AVDO2 in the following time intervals: (1) normocapnia (PaCO2 38-40 mmHg); (2) hypocapnia (PaCO2 28-30 mmHg); and (3) 30 min after mannitol (0.5 g/kg) infusion. RESULTS: Hyperventilation resulted in a significant decrease in SjVO2 (96% patients) and increase in AVDO2 (88% patients). Hypocapnia followed by mannitol administration led to a further decrease and increase of SjVO2 and AVDO2 in 72% and 68% patients, respectively. CONCLUSIONS: Mannitol may produce a further reduction in SjVO2 accompanied by an increase in AVDO2, suggesting a reduction of cerebral blood flow (CBF) during hyperventilation. Therefore, it should be given cautiously in neurosurgical patients under hyperventilation.

Adult↗
PubMed1993

Sympathetic activity enhances glucose-related ischemic injury in the rat.

BACKGROUND: Studies have shown that increased sympathetic activity or increased blood and brain glucose concentration worsen postischemic brain damage. The authors evaluated the interaction of plasma glucose with epinephrine and norepinephrine during incomplete cerebral ischemia in the rat using ganglionic blockade. METHODS: Rats were anesthetized with 25 micrograms.kg-1.h-1 fentanyl and 70% nitrous oxide in oxygen. Ganglionic blockade was produced in 30 rats using 8 mg/kg hexamethonium intravenously. Three plasma glucose ranges, low < 150 mg/dl, moderate = 150-300 mg/dl, and high > 300 mg/dl, were produced in each group. Ischemia was induced by unilateral carotid ligation and hemorrhagic hypotension to 30 mmHg for 30 min. Plasma norepinephrine and epinephrine were measured by radioimmunoassay. Neurologic outcome was evaluated daily for 3 days after ischemia. RESULTS: Ganglionic blockade decreased blood pressure before the start of ischemia and plasma epinephrine and norepinephrine during ischemia (P < 0.05). Neurologic outcome was significantly worse in rats with high glucose compared with low glucose concentrations with and without ganglionic blockade (P < 0.05). Neurologic outcome and stroke-related mortality were worse in rats with increased plasma epinephrine and norepinephrine compared with rats with ganglionic blockade when plasma glucose was less than 300 mg/dl (P < 0.05). CONCLUSIONS: These results indicate that increased concentration of catecholamines enhance glucose-related injury during incomplete ischemia in rats.

Animals↗
PubMed1993

Postoperative pain relief: lumbar and thoracic epidural morphine in thoracotomy.

Twenty-two patients undergoing thoracotomy were enrolled in a controlled, randomized trial to compare the effects of thoracic (group T) or lumbar (group L) epidural morphine in relieving postoperative pain. Epidural morphine was given as the patient first complained of pain in the recovery room. The effect of epidural morphine on pain relief was assessed by visual analogue scale and subjective grade. All patients were investigated 0, 10, 20, 30, 40, 50, 60, 75, 90, 105 and 120 minutes after a single bolus injection of epidural morphine. In assessment of pain relief by visual analogue scale, the difference between two groups was statistically significant (p < 0.05), evaluated 20, 30 and 40 minutes following treatment. There was no significant difference between two groups with regard to the effect of morphine as assessed by subjective grading. We concluded that thoracic epidural morphine took effect faster than lumbar epidural morphine. However, the effects of both kept similar since 50 minutes after morphine injection.

Adult↗
PubMed1990

The use of ketanserin for postoperative hypertension after abdominal surgery.

Eighteen adult patients who developed hypertension (systolic blood pressure greater than 160 mmHg, diastolic blood pressure greater than 90 mmHg or both) at the early recovery period after major abdominal surgery were included in the study. Following intravenous injection of 10 mg ketanserin, eleven out of eighteen patients (61%) had their systolic or diastolic blood pressure fell below the target mark (160 mmHg and 90 mmHg), and the decrease was statistically significant (p less than 0.01 up to 120 min). There was no statistically significant change in heart rate. Four patients (22%) responded to 20 mg of ketanserin. Three patients (17%) did not have significant decrease of the blood pressure after 20 mg of ketanserin and they received other antihypertensives instead. No severe hypotensive episode was noted. We concluded that ketanserin is a moderate, rapid-onset and safe antihypertensive agent in treating postoperative hypertension following major abdominal surgery.

Abdomen↗