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Wei-Zen Sun

Publications and source records attributed to Wei-Zen Sun.

At least 19 recordsLinked to original sources
PubMed2007

A minimal stress model for the assessment of electroacupuncture analgesia in rats under halothane.

The use of anesthetics in acupuncture analgesia is controversial. We evaluate a steady-state light anesthesia model to test whether minimal stress manipulation and reliable measurement of analgesia could be simultaneously achieved during electroacupuncture (EA) in animals. A series of experiments were performed. Firstly, EA compliance and tail-flick latencies (TFL) were compared in rats under 0.1%, 0.3%, 0.5%, 0.7%, or 1.1% halothane for 120min. Under 0.5% halothane, TFL were then measured in groups receiving EA at intensity of 3, 10 or 20 volt (V), 1 or 2mg/kg morphine, 20V EA plus naloxone, or control. Subsequently, the effect of EA on formalin-induced hyperalgesia was tested and c-fos expression in the spinal dorsal horn was analyzed. Rats exhibited profound irritable behaviors and highly variable TFL under 0.1% or 0.3% halothane, as well as a time-dependent increase of TFL under 0.7% or 1.1% halothane. TFL remained constant at 0.5% halothane, and needle insertion and electrical stimulation were well tolerated. Under 0.5% halothane, EA increased TFL and suppressed formalin-induced hyperalgesia in an intensity-dependent and naloxone-reversible manner. EA of 20V prolonged TFL by 74%, suppressed formalin-induced hyperalgesia by 32.6% and decreased c-fos expression by 29.7% at the superficial and deep dorsal horn with statistically significant difference. In conclusion, 0.5% halothane provides a steady-state anesthetic level which enables the humane application of EA stimulus with the least interference on analgesic assessment. This condition serves as a minimal stress EA model in animals devoid of stress-induced analgesia while maintaining physiological and biochemical response in the experiment.

Acupuncture Analgesia↗
PubMed2006

Oxidative stress during 1-lung ventilation.

OBJECTIVES: Resuming 2-lung ventilation from 1-lung ventilation might induce a re-expansion and reoxygenation effect. The oxidative stress during 1-lung ventilation/2-lung ventilation has not been studied, although severe complications, such as re-expansion pulmonary edema, were reported. Reactive oxygen species production and total antioxidant status assay levels were measured in this study during 1-lung ventilation/2-lung ventilation. The effects on extravascular lung water, cardiac output, and intrathoracic blood volume were also studied by using the Pulsion PiCCO system. METHODS: Twenty patients undergoing 1-lung ventilation/2-lung ventilation (>60 minutes) for video-assisted thoracoscopic surgery with minimal lung injuries were included in this study. Reactive oxygen species production was measured by means of lucigenin (detecting superoxide mainly) and luminol (detecting H2O2 and HOCl mainly) chemiluminescence. Reactive oxygen species production, total antioxidant status assay (by using the Randox TAS kit), extravascular lung water, cardiac output, and intrathoracic blood volume values were measured before 1-lung ventilation (T1), before resuming 2-lung ventilation (T2), 5 minutes after 2-lung ventilation (T3), and 30 minutes after 2-lung ventilation (T4). RESULTS: One-lung ventilation time was 118 +/- 33 minutes. Lucigenin chemiluminescence (but not luminol chemiluminescence) increased significantly at T3 and T4. Total antioxidant status decreased nonsignificantly. Extravascular lung water, intrathoracic blood volume, and permeability index values changed nonsignificantly after 2-lung ventilation. Cardiac output increased significantly at T4, and there is a negative correlation between cardiac output and extravascular lung water (r = -0.431, P < .005). CONCLUSIONS: Resuming 2-lung ventilation induces a massive superoxide production. Comparable extravascular lung water and intrathoracic blood volume and a nonsignificant decrease of total antioxidant status indicate adequate antioxidant capacity to counteract it. Severe oxidative injuries after 1-lung ventilation/2-lung ventilation should be considered in patients without adequate antioxidative capacity, such as those with cancer and trauma.

Adult↗
PubMed2006

Fatal massive hemorrhage caused by nasogastric tube misplacement in a patient with mediastinitis.

Nasogastric tube insertion is a routine procedure in medical care. However, misplacement of the tube can cause a variety of complications, which can be life threatening in some instances. We report a case of fatal hemorrhagic shock immediately after nasogastric tube insertion in a patient undergoing debridement by video-assisted thoracoscopic surgery for mediastinitis. Emergency endoscopy showed that the bleeding came from the nasogastric tube which had perforated the esophagus and possibly tore an intrathoracic large vessel. The nasogastric tube insertion was considered to have directly produced the perforation because no esophageal perforation had been found on preoperative endoscopy. Factors contributing to the risk of esophageal perforation in this case included coexisting mediastinitis, surgical manipulation, endotracheal intubation, inability to cooperate during general anesthesia, and repetitive advancement of the nasogastric tube. Prompt clamping of the nasogastric tube or delayed insertion after failed attempts might have improved the outcome. This report illustrates the complication of massive bleeding that can occur immediately after misplaced insertion of a nasogastric tube. Extraordinary care should be taken to avoid misplacement of the nasogastric tube during insertion.

Aged↗
PubMed2006

Cardioversion corrects cardiac arrhythmia and reverts the resultant reversed shunt flow direction during transcatheter closure of atrial septal defect--a case report.

Closure of atrial septal defect (ASD) is critically dependent on the shunt flow direction. However, shunt flow direction through ASD may change under variable clinical conditions. We present here a 53-year-old woman with a confirmed left-to-right shunt ASD prior to Amplatzer Septal Occluder placement. The development of atrial flutter during the procedure had been found to change the shunt from unidirectional to bidirectional and the procedure was then forced to a temporary halt. The cardiac arrhythmia and altered shunt direction simultaneously reverted to the old state after cardioversion. A successful placement of Amplatzer septal occluder was successfully performed afterward and she recovered uneventfully.

Atrial Flutter↗
PubMed2006

Two different anesthetic managements of a patient with von Gierke's disease.

Von Gierke's disease, a form of glycogen storage disturbance, is a rare metabolic disorder with important implications for anesthesiologists. It is caused by the lack of the glucose-6-phosphatase, which is necessary for the liver to convert glycogen to glucose. To avoid severe hypoglycemia, it is crucial to keep oral feeding at intervals 2-3 hr for maintaining a normal blood sugar level. The metabolic derangements of von Gierke's disease may result in serious complications in patients undergoing surgery and anesthesia. We report the anesthetic managements of a patient with von Gierke's disease in two operations with different encounters.

Adult↗
PubMed2006

Physicians' knowledge about pharmacological management of cancer pain--with special reference on their prescribing responses to simulated patients with cancer pain.

BACKGROUND: Cancer pain control is unsatisfactory in Taiwan. Insufficient knowledge about cancer pain on the part of physicians is an important factor responsible for ineffective cancer pain relief. Therefore, this study was to explore the knowledge deficits of physicians on the specific aspects of pharmacological management of cancer pain (PMCP) and their influences on the prescriptions to simulated patients in a southern medical center in Taiwan. METHODS: A set of self-designed questions was delivered to 234 licensed physicians with the responsibility to care for cancer patients and 111 (47.4%) questionnaires were completed and returned anonymously. RESULTS: Most of the physicians showed inadequate knowledge of the pharmacological management of cancer pain (3.34 +/- 0.49; range 1-5), which included the principle subscale (3.38 +/- 0.67) and the practice subscale (3.32 +/- 0.46). Crucial knowledge deficits of principle were identified in the preferential analgesic route and schedule. The severe practice knowledge deficits were on the meperidine, transdermal fentanyl, equianalgesic dose-conversion as well as analgesics for different pain types. Furthermore, physicians' knowledge deficits in the practice subscale, but not the principle subscale, correlated with their correct prescription of opioids to the simulated hepatoma cases. The correlates of physicians' PMCP knowledge deficits were: clinical specialty of medicine or surgery, less than 5 years or more than 10 years from medical school graduation, with limited volume of cancer pain patients being cared, and with personal unusual pain. CONCLUSIONS: The PMCP knowledge deficits were prevalent in physicians and thus influenced their prescription of opioids for the simulated cases. An active continuing education program on both the international guidelines and the essential practice skills should be implemented and intensified specifically upon subgroup physicians, to correct their misconceptions and consolidate their PMCP knowledge.

Adult↗
PubMed2005

Chimeric DNA vaccine reverses morphine-induced immunosuppression and tumorigenesis.

Although long-term use of morphine has been shown to promote tumor growth, the question whether tumorigenesis occurs as a result of an immunosuppressive effect remains to be investigated. In mice rendered tolerant to morphine, the efficacy and mechanism of a vaccination to rescue morphine-induced immunosuppression and prevent tumor growth was assessed both in vitro and in vivo. Herein, we found that morphine-injected mice exhibited higher tumor growth rates and lower percentages of CD8+ T lymphocytes. The mechanism of morphine suppression of immunity might be through the suppression of E7-specific CD8+ T lymphocyte proliferation and the promotion of apoptosis of these cells by the Bcl-2 and Bax pathways. The suppressive effect of E7-specific CD8+ T lymphocytes by morphine could be reversed by naloxone. We have previously shown that calreticulin linked with E7 (CRT/E7) could enhance the CD8+ T cell response and the anti-tumor effects (W. F. Cheng et al. (2001) J. Clin. Invest. 108, 669-678). CRT/E7 DNA vaccine could overcome the immunosuppressive effect of morphine and suppress tumor growth. Our findings reveal that long-term morphine treatment dose-dependently promotes tumor growth and a DNA vaccine may serve as a useful approach to treat the profound immunosuppressive function and prevent tumorigenesis after long-term morphine treatment.

Analgesics, Opioid↗
PubMed2005

Induction of rat hepatic cytochrome P-450 by ketamine and its toxicological implications.

Ketamine is a common intravenous anesthetic and a frequent drug of abuse, alone or in combination with cocaine. However, the pharmacokinetic effects of ketamine have not been fully investigated. This study determined the effects of ketamine on cytochrome P-450 (P-450)-dependent catalytic activities, protein levels, and hepatotoxicity using male Wistar rats treated with 10, 20, 40, or 80 mg/kg ketamine intraperitoneally twice daily for 4 d. Treatment with ketamine produced a dose-dependent increase of pentoxyresorufin O-dealkylation activity of liver microsomes. Treatment with 80 mg/kg ketamine resulted in 14-, 3-, and 2-fold rise in O-dealkylation of pentoxyresorufin, ethoxyresorufin, and methoxyresorufin of rat liver microsomes, respectively. The treatment produced 31% and 86% increases in 7-ethoxycoumarin O-deethylation and erythromycin N-demethylation, respectively. In addition, aniline hydroxylation activity was elevated by 62%. Protein blot analysis of liver microsomal proteins revealed that 80 mg/kg ketamine induced P-450 1A, 2B, 2E1, and 3A proteins by 2-, 13-, 2-, and 2-fold, respectively. In reversibility study, ketamine-induced pentoxyresorufin O-dealkylation, 7-ethoxycoumarin O-deethylation, erythromycin N-demethylation, and methoxyresorufin O-demethylation activities of liver microsomes prepared from rats 4 d after ketamine treatment were 75%, 48%, 29%, and 38% lower than the respective activities of liver microsomes prepared from rats 1 d after treatment. Protein blot analysis showed that ketamine-induced P-450 2B1/2 proteins also decreased in a time-dependent manner in 4 d. In hepatotoxicity study, treatment of rats with 1 ml/kg CCl4 produced a 7-fold increase in serum alanine aminotransferase activity level and a 17-fold rise in rats pretreated with 80 mg/kg ketamine for 4 d. Treatment of ICR mice with 120 mg/kg cocaine produced a 17% mortality, whereas the same dose of cocaine produced a 50% mortality in mice pretreated with ketamine. Treatment of mice with 100 mg/kg cocaine produced a 76-fold increase in serum alanine aminotransferase activity level and a 260-fold rise in mice pretreated with 80 mg/kg ketamine for 4 d. The present study shows that ketamine induces the expression of multiple forms of P-450 in rat liver microsomes and increases CCl4-induced liver toxicity and cocaine-mediated acute toxicity. Other potential pharmacological or toxicological events related to ketamine use need to be further explored.

Anesthetics, Dissociative↗
PubMed2005

Denaturing high performance liquid chromatography screening of ryanodine receptor type 1 gene in patients with malignant hyperthermia in Taiwan and identification of a novel mutation (Y522C).

We performed the present study to identify the mutation in patients in Taiwan with malignant hyperthermia (MH). We also test the hypothesis that a denaturing high-performance liquid chromatography (DHPLC) protocol can be used for mutation detection in these patients. We identified five Taiwanese patients with typical clinical presentations of MH after general anesthesia. We also enrolled 50 healthy volunteers. Polymerase chain reaction was used to amplify the ryanodine receptor (RYR1) gene mutation hot spots and DHPLC techniques were used to screen for mutations. Upon detection of a heterozygous elution pattern in DHPLC analysis, DNA sequencing reaction was performed to identify the nucleotide variations. We identified a RYR1 mutation in all 5 patients with MH. There were 4 different mutations in the 5 patients: Tyr522Cys, Arg552Trp, Val2168Met, and Thr2206Arg. Among the 5 patients, 2 unrelated patients had the same Thr2206Arg mutation. Three of the mutations had been reported before, but the Tyr522Cys mutation was novel. None of the MH-related mutations were found in the control group. In conclusion, we identified RYR1 mutations in 5 Taiwanese patients with MH using a DHPLC-based approach. A DHPLC-based genetic test may be developed as a noninvasive and convenient test for MH.

Adolescent↗
PubMed2005

The optimal injection time of alfentanil for blunting circulatory responses to tracheal intubation.

BACKGROUND: The aim of this study is to investigate the optimal injection time of alfentanil during induction of anesthesia to blunt the circulatory responses induced by laryngoscopy and tracheal intubation. METHODS: Seventy-five patients of ASA class I or II were randomly assigned to five groups. Group I was the placebo group in which the patients received normal saline 2 ml just before induction. Patients in groups II, III, IV and V received alfentanil 10 microg/kg at 5, 3, 1 and 0.5 min before intubation respectively. Anesthesia was maintained with 1.5% isoflurane and nitrous oxide in 50% oxygen (2:2 L/min). The patients' heart rate and blood pressure before and after intubation were documented and compared. The occurrence of adverse effects was also recorded. RESULTS: Patients' demographic data, baseline hemodynamic profile and the laryngoscopic time did not differ among the five groups. The patients in groups II, III and IV showed decreased heart rate compared with group I within 3 min after intubation. The patients in group V like those in group I did not show a reduction in heart rate 1 min after intubation. The patients in groups II, III, IV and V all showed reduced systolic blood pressure and rate-pressure product (RPP) 2 min after intubation. The occurrence of hypotension and bradycardia was not different among the five groups; hypertension and high RPP were less in groups II, III and IV as compared with group I. Ninety-three percent patients in group II and group III suffered from dizziness after alfentanil administration. One patient in group II had nausea and another one patient displayed hypoxemia after alfentanil administration. CONCLUSIONS: Considering equal effectiveness and fewer side effects, one minute before intubation is the optimal injection time of alfentanil to blunt the circulatory responses induced by laryngoscopy and tracheal intubation.

Adult↗
PubMed2005

Starting dose of gabapentin for patients with post-herpetic neuralgia--a dose-response study.

BACKGROUND: Gabapentin has been shown to provide pain relief for post-herpetic neuralgia at dosage of 1200 to 2400 mg/day. However, the initial dosing strategy has not been thoroughly investigated. The purpose of this study was to establish the initial dosing strategy in the treatment of the gabapentin-naive patients with post-herpetic neuralgia. METHODS: This clinical study was an open-label, randomized, time-sequence and controlled trial. Each gabapentin-naive subject was allocated to receive either 200 mg (100 mg, twice daily), 400 mg (100 mg, four times daily), or 600 mg (200 mg, three times daily) of gabapentin for three days. The analgesic effect and occurrence of dizziness, drowsiness, and fatigue were assessed at day 0 and day 3. RESULTS: A total of 61 subjects (32 male/29 female) were enrolled in this study. The intensity of pain was greatly improved in all three groups after three days of treatment (visual analog scale decreased from 6.5 +/- 1.6 to 4.5 +/- 2.1, P < 0.05). There was no statistically significant difference among subjects taking 200 mg, 400 mg, or 600 mg with respect to dizziness, drowsiness or fatigue. CONCLUSIONS: This study shows that elderly gabapentin-naive subjects no matter whether receiving 200, 400 or 600 mg/day of gabapentin benefited a moderate pain relief with minimal side effects at the first three days of treatment. Since starting with a minimal dose of 200 mg/day did not offer a better reduction of side effects, we suggest that 600 mg/day gabapentin could be a safe and effective starting dose for patients with post-herpetic neuralgia.

Adult↗
PubMed2005

Differential analgesic effect of tenoxicam on post-cesarean uterine cramping pain between primiparous and multiparous women.

BACKGROUND AND PURPOSE: Uterine cramping pain is related to prostaglandins, which are mediated by cyclooxygenase. However, it is unknown whether the analgesic effects of the non-selective cyclooxygenase inhibitor tenoxicam are different between primiparous and multiparous women. This placebo-controlled, double-blind study compared the analgesic effect of tenoxicam on post-cesarean uterine cramping pain in primiparous and multiparous women. METHODS: Forty primiparous women and 40 multiparous women who were scheduled for elective cesarean delivery were allocated into the following 4 groups: saline-primipara (SP) group, tenoxicam-primipara (TP) group, saline-multipara (SM) group, and tenoxicam-multipara (TM) group. Saline or 20 mg tenoxicam was intravenously injected immediately after clamping of the umbilical cord. All patients received patient-controlled analgesia for postoperative pain control. Resting wound pain, uterine cramping pain, morphine consumption, and morphine-related side effects were evaluated at 4 and 24 hours after surgery. RESULTS: At 24 hours after surgery, tenoxicam-related relief of uterine cramping pain was 2.1 in primiparous women (visual analog scale: SP 5.6 (4.4-6.8) minus TP 3.5 (2.2-4.9); p < 0.01). The tenoxicam-related morphine-sparing effect was 14 mg (45%) in primiparous women (SP 31.4 mg (23.9-38.8) minus TP 17.4 mg (11.6-23.2); p < 0.01). The tenoxicam-related relief of uterine cramping pain and tenoxicam-related morphine-sparing effect were not significant in multiparous women. CONCLUSIONS: This study revealed that the analgesic effect of tenoxicam on post-cesarean uterine cramping pain is greater in primiparous women than in multiparous women. Further studies are required to determine whether a higher dosage of tenoxicam is beneficial to reduce uterine cramping pain in multiparous women.

Adult↗
PubMed2004

Prolonged retraction on the normal common carotid artery induced lethal stroke after cervical spine surgery.

STUDY DESIGN: Case report. OBJECTIVE: To report a previously undescribed complication of prolonged retraction on the normal common carotid artery after anterior cervical spine surgery. SUMMARY OF BACKGROUND DATA: Previous study showed that prolonged retraction could decrease the blood flow of the common carotid artery during anterior cervical spine surgery. A case report revealed that prolonged retraction could induce the formation of thrombosis in the atherosclerotic common carotid artery. METHODS: Notes review. Computed tomography of the brain was performed on the first and the fourth postoperative day. Carotid Doppler ultrasound and transcranial Doppler ultrasound were performed to evaluate the left common carotid artery and the left intracranial cerebral arteries. RESULTS: After lengthy anterior cervical spinal surgery, the patient did not regain his consciousness during the stay in the postoperative care unit. Large infarction of left cerebral hemisphere was revealed by computed tomography. The patient died on the seventh postoperative day of perioperative lethal stroke. CONCLUSION: We suggest that prolonged retraction, even on the normal common carotid artery, could induce lethal stroke after anterior cervical spine surgery. We recommend that retractor should be placed carefully and cerebral perfusion should be maintained adequately.

Aged↗
PubMed2004

Inhibition of neuropathic pain by a potent disintegrin--triflavin.

Injury to peripheral nerves may result in severe and intractable neuropathic pain. Many efforts have been focused on the elucidation of the mechanisms of neuropathic pain. It was found here that integrin plays an important role in the induction of neuropathic pain and treatment of disintegrin is able to attenuate neuropathic pain. The rats were induced hyperalgesia by tightly ligating the L5 spinal nerve and cut just distal to the ligature on one side. Mechanical and thermal stimuli were applied in the middle dermatome of the hind paw. Epidural administration of triflavin (TFV), an arginine-glycine-aspartic acid (RGD) containing disintegrin, inhibited hyperalgesia induced by either mechanical or thermal stimulation. Immunohistochemistry showed that the sprouting of sympathetic nerves into DRG by neuropathic surgery was markedly inhibited by TFV. Beta 1 integrin mRNA of L5 DRG increased immediately 1 day after tight ligation and cut of L5 spinal nerve. However, beta 1 integrin mRNA in uninjured L4 DRG increased later on Day 3 after surgery. On the other hand, alpha-CGRP precursor mRNA decreased in ipsilateral L5 DRG but increased in L4 DRG after neuropathic surgery. Immunohistochemistry shows that beta 3 integrins of L5 as well as L4 increased in response to neuropathic surgery and administration of triflavin antagonized the increasing action. These results suggest that there is interaction between injured and uninjured neurons and the induction of neuropathic pain is related to neuronal sprouting. Disintegrin is able to inhibit neuronal sprouting and the induction of hyperalgesia induced by peripheral nerve injury and may thus be a new category of drugs to be developed for the treatment of neuropathic pain.

Animals↗
PubMed2004

Differential morphine effects on short- and long-latency laser-evoked cortical responses in the rat.

Evoked potential and ensemble neuronal activities were used to study the responses of the primary sensorimotor cortex (SmI) to noxious CO(2) laser irradiation of the middle part of the tail in conscious behaving rats. The hypothesis that systemic morphine treatment preferentially attenuates the longer-latency laser-evoked cortical responses was also tested. Laser-evoked potentials (LEPs) and multiple single-unit (SU) activities were, respectively, recorded from chronically implanted stainless-steel screws and microwire electrodes. When examined individually, many SmI neurons showed either short-latency (<100 ms) or long-latency (300-500 ms) responses to laser irradiation. These neurons are widely dispersed in the tail region and hind limb region of the SmI, and also in the forelimb and head regions of the primary motor cortex (MI). Quantitatively, a higher percentage of neurons in the SmI tail region responded with shorter latencies compared to those in the SmI hind limb region or in the MI. When responses of many simultaneously recorded SU were examined together, short-latency and long-latency SmI ensemble activities matched the LEP1 and LEP2, respectively. Systemic morphine significantly attenuated the long-latency but not the short-latency component in both LEPs as well as ensemble neuronal activity in the tail region of the SmI. These effects were blocked by naloxone pretreatment.

Action Potentials↗