Increase in excitatory amino acid concentration and transporters expression in osteoarthritic knees of anterior cruciate ligament transected rabbits.

OBJECTIVE: The present study aimed to determine the role of excitatory amino acids (EAAs) and EAA transporters (EAATs) in an osteoarthritis (OA) model of rabbit knees. METHODS: OA was induced in New Zealand white male rabbits by anterior cruciate ligament transection (ACLT) in one knee of one hind limb; the other knee left unoperated. Rabbits that received ACLT of knee were assigned to the ACLT group (n=6), while a sham-operated group (n=6) underwent arthrotomy with no ACLT. Six naïve rabbits that received no surgery were used as normal control. The width of the knee joint was measured to determine the severity of joint inflammation. Before operation and at 10, 20, and 30 weeks after operation, knee joint dialysates were collected by microdialysis and assayed for EAAs by high-performance liquid chromatography. Gross morphology and histopathology and EAATs glutamate/aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1) expression in the articular cartilage of the knees were evaluated by immunohistochemistry and western blot analysis. RESULTS: In the ACLT knees, a significant increase in the joint width was observed (5.3+/-0.9 mm, P<0.05) at 30 weeks after operation, while the sham-operated and naïve knees showed no difference as compared with the basal values. The concentrations (microM) of aspartate and glutamate in knee dialysates at 30 weeks after ACLT in naïve, sham, and ACLT were 0.36+/-0.07 and 4.5+/-1.10; 0.38+/-0.09 and 4.61+/-1.11; 0.67+/-0.18 and 9.71+/-2.89, respectively. Levels of glutamate and aspartate in the dialysates obtained from the ACLT knees increased by 213.3+/-29.6% and 187.5+/-33.8% (P<0.05) when compared to those in the sham-operated knees. Both naïve and ACLT chondrocytes were positively stained by antibodies against GLAST and GLT-1. GLAST and GLT-1 protein expressions were significantly increased in the ACLT knees (P<0.05). CONCLUSION: Our findings indicate an involvement of EAAs and EAATs in the pathogenesis of OA in ACLT rabbits.

N-Methyl-D-aspartate receptor antagonist MK-801 attenuates morphine tolerance and associated glial fibrillary acid protein up-regulation: a proteomic approach.

BACKGROUND: It is well known that long-term morphine administration results in tolerance, which limits the clinical use of this drug in pain management. METHODS: Male Wistar rats were randomly assigned to receive one of four different infusions: morphine [15 microg/h, intrathecal (i.t.)], saline, MK-801 (5 microg/h, i.t.) plus morphine (15 microg/h, i.t.), or MK-801 (5 microg/h, i.t.) alone. RESULTS: Morphine infusion induced a maximal antinociceptive effect on day 1 and tolerance on day 3, and the maximal anti-receptive tolerance was observed on day 5. Co-infusing MK-801 with morphine attenuated morphine's anti-receptive tolerance. Two-dimensional gel electrophoretic analysis of spinal proteins revealed that eight protein spots were up-regulated in morphine-tolerant rats, and that they were significantly inhibited by MK-801 co-infusion. Among the up-regulated proteins, glial fibrillary acid protein (GFAP), a glial-specific maker, was identified by mass spectrometry. This finding was also confirmed by Western blot analysis. CONCLUSION: Using proteomic analysis, we identified eight GFAP protein spots that were up-regulated in the dorsal horn of morphine-tolerant rat spinal cords. This up-regulation was partly inhibited by N-methyl-D-aspartate receptor antagonist MK-801 co-infusion, which suggests that GFAP protein can be considered to be a pathogenesis marker of morphine tolerance.

Changes in the levels of nitric oxide synthase and protein kinase C gamma following kainic acid receptor activation in the rat spinal cord.

In this study, we evaluated the levels of nitric oxide synthase, both neuronal and induced (nNOS and iNOS, respectively), cyclooxygenase-1 and 2 (COX-1 and COX-2) and protein kinase C gamma (PKCgamma) and correlated these with algogenic behavior following spinal kainic acid (KA) receptor activation in rats. Thirty adult male Sprague-Dawley rats were randomly assigned into six groups (n=5). Groups A, B, and C received 0.5 g kainic acid intrathecally and were analyzed at 3, 6, 24 h after injection, respectively. Groups D, E, and F received saline and were analyzed at 3, 6, 24 h after injection, respectively. We observed for behavioral changes in the rats following intrathecal KA injection and analyzed the protein levels of NOS, COX and PKCgamma by Western blotting techniques. Importantly, we clarified the potential roles of PKCgamma in the regulation of nNOS and COX-2 following intrathecal injection with KA in the rat spinal cord. COX-2 protein was detected but not significantly changed in the lumbosacral spinal cord at 3, 6, and 24 h following intrathecal KA injection (P>0.05). In contrast, nNOS protein was detected at higher levels in comparison with normal spinal cord at 6 and 24 h after intrathecal administration of KA (P<0.05). PKCgamma also increased significantly at 3, 6, and 24 h after intrathecal KA injection when compared with the baseline level (P<0.05). On the other hand, COX-1 and iNOS were not detected in either normal or KA treated spinal cords. These results provide strong in vivo evidence to support the idea that nNOS but not COX-2, plays an important role in spinal KA receptor activation. Furthermore, up-regulation of PKCgamma is involved in KA induced algogenic behavior in rats.

Accidental shock during epidural anesthesia in a patient with NSAID-induced hyporeninemic hypoaldosteronism.

An obese man suffered cardiac arrest twenty minutes after receiving epidural anesthesia for incision and debridement of wound over the right leg. The patient's condition stabilized after emergent cardiopulmonary resuscitation. It was found that the patient had been self-administering an herbal drug continuously for a year and a half, and that this drug contained ethoxybenzamide, which is a nonsteroidal anti-inflammatory drug (NSAID). Low plasma renin and aldosterone levels were noted from the blood sample taken at the time of the cardiac arrest. The cardiac arrest was believed to be related to NSAID-induced hyporeninemic hypoaldosteronism, superimposed with epidural anesthesia-induced sympathectomy.

Comparison of epidural butorphanol plus clonidine with butorphanol alone for postoperative pain relief.

BACKGROUND: Epidural butorphanol has been shown to produce effective analgesia with less side effects than that of morphine but relatively short duration. Clonidine, an alpha 2-adrenergic agonist, has been reported to provide [corrected] pain relief by epidural administration. Furthermore, epidural clonidine has been shown to potentiate the analgesic effect of epidural morphine. The present study was undertaken to evaluate the analgesic and side effects of epidural administration (Ep) of butorphanol and clonidine. METHODS: After giving their consents, 60 adult patients scheduled for abdominal surgeries were enrolled in this study. Prior to anesthesia induction, indwelling lumbar epidural catheters were placed in all patients who then received general anesthesia with inhalation anesthetic without narcotic analgesics. In the postoperative period, when the patients first complained of pain, they were divided into 2 equal groups of 30 patients each in a randomized and double blinded fashion with Group I receiving Ep butorphanol 0.5 mg and Group II receiving Ep butorphanol 0.5 mg plus clonidine 75 micrograms. All patients were observed for pain relief, sedation, vital signs, arterial blood gas studies and adverse effects for 12 h. RESULTS: Onset of pain relief with epidural butorphanol began at 5 min and peaked at 20-30 min with a duration of action lasting 4-6 h. The combination of butorphanol and clonidine had numerically superior pain relief than that of butorphanol for the first 30 min but it did not attain statistical significant difference. The duration of action with the combination group was similar to that of butorphanol alone. Incidence of adverse effects were similar in both groups except that hypotension and more pronounced sedation were observed in Group II. CONCLUSIONS: Our study showed that the addition of clonidine to epidural butorphanol did not enhance its analgesic effect in any significant manner nor did it reduce the adverse effects. This combination does not seem to offer any advantage for clinical use.

Retention of broken central venous catheters in pulmonary artery and inferior vena cava--a case report.

Central venous catheterization (CVC) has become an important maneuver both for measuring the central venous pressure and for carrying out long-term intravenous alimentation. Furthermore, a central vein may be needed for the rapid restoration of blood volume in condition of acute hemorrhage with difficulties establishing of a peripheral cannulation. However, complications related to either the venipuncture or the presence of catheters in the central venous system were reported. The case we reported here had two ruptured catheter fragments retained in the great vessels, one in the right subclavian vein and the other one in the femoral vein during CVC. They migrated to the pulmonary artery and inferior vena cava, and were finally removed through open sternotomy with pulmonary arteriotomy and exploration of common iliac vein two weeks later. This was an unusual and possibly fatal complication.

Intermittent bolus versus patient-controlled epidural morphine for postoperative analgesia.

BACKGROUND: Patient-controlled epidural analgesia (PCEA) is a technique that combines the flexibility and convenience of PCA with the intrinsic analgesic efficacy of epidurally administered opioids. The aim of this study is to compare the analgesic and side effects of intermittent bolus injections of epidural morphine with PCEA using morphine during the first 24 h after elective low abdominal surgery. METHODS: Sixty patients were randomly assigned into two groups. Patients in group I (n = 30) received 3 mg epidural morphine at an 8-hour interval after surgery. Patients in group II (n = 30) received 2 mg epidural morphine after surgery and patient-controlled analgesia device was processed to deliver morphine 0.15 mg/h, 0.15 mg/bolus. All patients were observed for pain relief and adverse effects for 24 h. RESULTS: Mean morphine consumption was 9 mg for epidural morphine group and 6.87 +/- 0.27 mg for PCEA group. Although the PCEA group utilized significantly less morphine (p < 0.05), pain and sedation scores were similar in the two groups. Pruritus occurred more frequently in the epidural morphine group (63%) than in the PCEA group (33%). Frequency and severity of nausea and vomiting were similar in the two groups. CONCLUSIONS: PCEA with morphine decreases morphine consumption and with less adverse effects than intermittent bolus of epidural morphine. PCEA with morphine is an acceptable alternative to epidural morphine after low abdominal surgery.

Carbon dioxide laser induced airway fire during larynx surgery: case report.

The precision intrinsic hemostatic properties of the laser have led to its wide use in modern clinical medicine especially in microscopic airway surgery. However, the intense heat generated by the high energy density of the surgical laser can convert combustible tubes into veritable torches, cause catastrophic fires, and result in severe injury to the patient. This is of particular importance when high energy is used on the continuous mode or when the endotracheal tube is repeatedly hit by the laser at the same spot. Most reported laser-induced complications result from the laser beam inadvertently falling on the areas that are not intended to be exposed. We report a case of a trans-tracheostomy tube fire occurring during carbon dioxide (CO2) laser surgery. Aluminum-tape wrapping did not prevent this complication. It was found that the ignition of a trans-tracheostomy tube was caused by the laser striking an unprotected portion of the tube during resection of granuloma of the trachea.

Effect of thiopental, propofol, and etomidate on vincristine toxicity in PC12 cells.

Neurotoxicity is the dose-limiting side-effect of vincristine in cancer therapy. Using the nerve growth factor (NGF)-dependent neurite outgrowth and cell proliferation of the PC12 pheochromocytoma cell line as an in vitro assay, the protective effect of different intravenous anesthetics was assessed. Vincristine (1 nmol/L) significantly decreased the percentage of neurite-forming cells from 68% +/- 9% to 27% +/- 7% within a 3-day incubation period. The longer neurites (> 2 x cell body) in particular proved to be extremely sensitive to vincristine (from 17% +/- 4% to 0% of total neurite-expressing cells). Flow cytometry results revealed an S-phase percentage of 15.85% +/- 3.25% after NGF induction, with vincristine reducing this percentage to 0.68% +/- 0.38%. Reversal of the inhibitory effect of vincristine was noted in the cells treated with thiopental or propofol but not etomidate. Bicuculline partially antagonized the protective effect of thiopental and propofol in both studies. We conclude that thiopental and propofol, but not etomidate, have a protective effect in vincristine-induced neurotoxicity. The protective effect produced by thiopental and propofol is probably secondary to activation of GABAA receptors.

Gene therapy for bladder pain with gene gun particle encoding pro-opiomelanocortin cDNA.

PURPOSE: Interstitial cystitis is a bladder hypersensitivity disease associated with bladder pain that has been a major challenge to understand and treat. We hypothesized that targeted and localized expression of endogenous opioid peptide in the bladder could be useful for the treatment of bladder pain. Pro-opiomelanocortin (POMC) is one of such precursor molecules. In this study we developed a gene gun method for the transfer of POMC cDNA in vivo and investigated its therapeutic effect on acetic acid induced bladder hyperactivity in rats. MATERIALS AND METHODS: Human POMC cDNA was cloned into a modified pCMV plasmid and delivered into the bladder wall of adult female rats by direct injection or the gene gun. Three days after gene therapy continuous cystometrograms were performed using urethane anesthesia by filling the bladder (0.08 ml per minute) with saline, followed by 0.3% acetic acid. Bladder immunohistochemical testing was used to detect endorphin after POMC cDNA transfer. RESULTS: The intercontraction interval was decreased after intravesical instillation of acetic acid (73.1% or 68.1% decrease) in 2 control groups treated with saline or the gene gun without POMC cDNA, respectively. However, rats that received POMC cDNA via the gene gun showed a significantly decreased response (intercontraction interval 35% decreased) to acetic acid instillation, whereas this antinociceptive effect was not detected in the plasmid POMC cDNA direct injection group. This effect induced by POMC gene gun treatment was reversed by intramuscular naloxone (1 mg/kg), an opioid antagonist. Increased endorphin immunoreactivity with anti-endorphin antibodies was observed in the bladder of gene gun treated animals. CONCLUSIONS: The POMC gene can be transferred in the bladder using the gene gun and increased bladder expression of endorphin can suppress nociceptive responses induced by bladder irritation. Thus, POMC gene gun delivery may be useful for the treatment of interstitial cystitis and other types of visceral pain.

Effect of pretreatment with ketorolac on propofol injection pain.

BACKGROUND: : Pain on injection is still a major problem with propofol. We performed this study to compare different doses of intravenous (i.v.) ketorolac with and without venous occlusion and its effect on the incidence and the severity of the pain after propofol injection. METHODS: We conducted a prospective, randomized and double-blind study of 180 patients (20-60 years of age.) scheduled to undergo elective surgery. Six groups of patients were generated: group A received normal saline (NS) 2 ml i.v.; groups B, C, D received ketorolac 10 mg in 2 ml NS with venous occlusion (VO) and a subsequent propofol injection at either 30, 60 or 120 s; groups E and F received ketorolac 15 mg and 30 mg in 2 ml NS and propofol was injected after 60 s. The pain perception was assessed during injection of propofol in all patients. RESULT: : The incidence of propofol-associated injection pain was for A: 46.7%; B: 43.4%; C: 23.3%; D:16.7%; E: 20%, and F: 10%. The incidence of pain following propofol injection was reduced by i.v. ketorolac 10 mg with venous occlusion for 120 s. Furthermore, i.v. ketorolac 15 mg and 30 mg but not 10 mg following propofol injection after 60 s without venous occlusion revealed significant pain reduction when compared to saline group. There was no difference in venous sequelae at 7 days postoperatively between the groups. CONCLUSION: Our results suggested that pretreatment with i.v. 15 and 30 mg ketorolac reduces pain following propofol injection. Moreover, pretreatment with i.v. ketorolac 10 mg with venous occlusion for 120 s achieves the same pain relief effect.

Gene-gun particle with pro-opiomelanocortin cDNA produces analgesia against formalin-induced pain in rats.

Endogenous opioid peptides play an essential role in the intrinsic modulation and control of inflammatory pain, and could be therapeutically useful. These opioid peptides are synthesized as parts of larger precursor molecules. One such precursor molecule is pro-opiomelanocortin (POMC). In this study, we developed a gene-gun method for the transfer of POMC cDNA in vivo, and investigated its therapeutic effect on inflammatory pain in a rat model of formalin-induced pain. Human POMC cDNA was cloned into a modified pCMV plasmid and delivered to the skin of rats by gene gun. Three days after gene-gun injection, 1% formalin was injected. Endorphin levels were measured in the serum and skin after the formalin test, and skin histology was used to detect endorphin after green fluorescent protein (GFP; control) or POMC cDNA transfer. There was no significant difference in the results of acute nociceptive tests between the experimental and control groups. There was also no difference in response between the groups to phase 1 of the formalin test. However, rats which received POMC cDNA via gene-gun injection showed a significantly reduced response in phase 2 of the formalin test. Endorphin immunoreactivity in the skin increased approximately three- to four-fold in experimental animals compared with GFP-treated controls at day 3 after injection. The phase 2 response in animals treated with formalin and naloxone did not differ significantly from the control, implying that the analgesic effects of POMC cDNA particle injection in phase 2 of the formalin test are reversed by naloxone. There are two major findings from this study. First, in vivo DNA delivery by gene gun to the skin is feasible. Second, the production of beta-endorphin is insufficient to block phasic pain, but is effective against sensitization of the afferent neurons during phase 2 of the formalin test.