Ching-Yue Yang

Inhibition of the cyclic adenosine monophosphate pathway attenuates neuropathic pain and reduces phosphorylation of cyclic adenosine monophosphate response element-binding in the spinal cord after partial sciatic nerve ligation in rats

BACKGROUND:Recent reports have identified a role for cyclic adenosine monophosphate (cAMP) transduction in nociceptive processing. Spinal activation of the cAMP induced gene transcription through the activation of protein kinase A and cAMP response element-binding protein (CREB). Intrathecal injection of protein kinase A inhibitor reversed the mechanical hyperalgesia, whereas injection of CREB antisense attenuated tactile allodynia caused by partial sciatic nerve ligation (PSNL) in rats. In the present study, we aimed to assess the effects of spinal cAMP transduction on the nociceptive processing in a chronic neuropathic pain model. METHODS:PSNL was performed in male Sprague-Dawley rats 1 wk after intrathecal catheterization. Nociception to mechanical and thermal stimuli was assessed at the hindpaw 2 h, 3, 7, and 14 days after PSNL. The effects of adenylate cyclase inhibitor, SQ22536 (0.7 &mgr;mol, intrathecal) on these nociceptions were evaluated. Changes in the expression and immunoreactivity of CREB and its phosphorylated proteins (CREB-IR and pCREB-IR) in the dorsal horn of the spinal cord were also measured. RESULTS:The expression of CREB-IR and pCREB-IR proteins was shown to increase for 2 wk after PSNL. The increase in pCREB was partially reversed by the blockade of the cAMP pathway in the early 3 days, with a parallel increase in mechanical and thermal withdrawal thresholds. CONCLUSION:These results revealed the possible contribution of an increase in pCREB to the PSNL-induced tactile allodynia and thermal hyperalgesia. Modulation of the cAMP pathway may be clinically relevant if early intervention can be achieved in patients with chronic neuropathic pain.

Propofol inhibits medullary pressor mechanisms in cats

PurposePropofol may cause hypotension and the mechanism is complex. The present study was designed to determine the direct actions of propofol in medulla of cats.MethodsMean systemic arterial pressure (MSAP), heart rate (HR) and cardiac contractility (dp/dt) were compared before and after administration of propofol through the femoral vein (2, 3 or 4 mg · kg−1), vertebral artery (1 mg · kg−1) or the lateral cerebral ventnricle (0.5 mg · kg−1) in eight anaesthetized cats. To study the direct effect of propofol in medulla, pressor areas of the dorsomedial medulla (DM) and rostral ventrolateral medulla (RVLM), or the depressor area of the caudal ventrolateral medulla (CVLM) were first identified with electrical stimuli and then confirmed by pressure microinjection of glutamate (Glu, 0.25M, 30 nl) via a multibarrel-micropipette in 28 cats. One hour later, propofol (0.001%, 50 nl) was microinjected at the same site. Electrical stimulation and Glu were applied again to compare changes of SAR HR and dp/dt with that of the control.ResultsPropofol dose-dependently decreased SAR HR and cardiac contractility. The percent increase of MSAP induced by Glu were reduced by propofol in DM (59 ± 3 % vs 13 ± 2 %, n = 11.P < 0.01) or in RVLM (56 ± 4 % vs 18 ± 2 %, n = 9,P < 0.01). In CVLM, propofol slightly but not significantly increased the depressor responses elicited by Glu (−27 ± 2 %vs ∼-33 ± 3 %. n = 5,P > 0.05).ConclusionOur results show that propofol principally inhibits the vasomotor mechanism in the dorsomedial and ventrolateral medulla to effect its hypotensive actions.RésuméObjectifLe propofol produit de l’hypotension par un mécanisme complexe. Cette étude avait pour objectif de délimiter sur le bulbe du chat l’activité directe du propofol.MéthodesLa pression artérielle systémique moyenne (PASM), la fréquence cardiaque (FC) et la contractilité cardiaque (dp/dt) ont été comparées avant et après l’injection de propofol dans la veine fémorale (2, 3 et 4 mg · kg−1), l’artère vertébrale (1 mg · kg−1) et le ventricule cérébral latéral (0, 5 mg · kg−1) chez six chats anesthésiés. Pour étudier les effets bulbaires directs du propofol, les zones vasopressives dorsomédiane (DM) et ventrolatérale rostrale (BVLR) bulbaires, ou la zone vasodépressive ventrolatérale caudale (BVLC) bulbaire ont d’abord été identifiées par stimulation électrique et confirmées par micro-injection sous pression de glutamate (Glu 0.25M, 30 ml) à l’aide d’une micropipette à plusieurs banllets chez 28 chats. Une heure plus tard, du propofol (0, 001%, 50 nl) était injecté au même site. Lélectrostimulation et Glu étaient appliqués encore une fois pour comparer les changements de PAS. le FC et de dp/dt avec ceux du contrôle.RésultatsDépendaminent de la dose, le propofol diminue PAS, FC etdp/dt. En pourcentage, l’augmentation de PASM induite par Glu était réduite par le propofol dans DM 159 ± 3 %va 13 ± 2 %. n= 11,P < 0, 01) ou dans BLVR (56 ± 4 %vs 18± 2%, n = 9, P < 0.01). Dans BLVM, le propofol a augmenté légèrement mais non significativement les réponses vasodépressives induites par Glu (−27 ± 2 % vs −33 ± 3 %. n = 5,P < 0, 05).ConclusionNos résultats montrent que l’action hypotensive du propofol est causée par l’inhibition du mécanisme vasomoteur au niveau des zones bulbaires dorsomédiane et ventrolatérale.

Chemical Burn Caused by Providone-iodine Alcohol Solution-A Case Report

Burns associated with chemical disinfectants for skin preparation are rare. Skin irritation and maceration associated with pressure factors may contribute to its occurrence. We report a 24-year-old female with thyroid tumor who was admitted for subtotal thyroidectomy. After anesthetic induction, the patient was placed in the supine position with the trunk elevated to 20 degree. The skin over the anterior neck was sterilized with 10% Povidone-iodine (PI) alcohol solution. After a 3-hour surgery, the patient complained of burning pain over the back at the recovery room. Physical examination revealed a 9 x 11 cm area of skin lesion partially thickened amid on the middle of the back suggestive of chemical burn. After conservative treatment, she was discharged uneventfully 4 days later. Upon follow-up, the wound was seen to heal with minimal scarring within 3 weeks.

Propofol ensures a more stable A-line ARX index than thiopental during intubation

BackgoundThe A-line autoregressive modelling with exogenous input index (AAI) is a new method of assessing depth of anesthesia. We examined the effects of tracheal intubation on the AAI and hemodynamics during induction of anesthesia with propofol compared with thiopental in patients aged over 50 yr. Methods: 40 patients scheduled for a laminectomy, posterior spinal fusion, vertebroplasty, or total hip replacement, ASA physical status I or II and aged over 50 yr, were randomly divided into two groups. Thiopental 5 mg·kg-1 iv, fentanyl 2.5 μg·kg-1 iv, and rocuronium 0.7 mg·kg-1 iv were used in the thiopental group (n = 20) for anesthetic induction; the same protocol was used in the propofol group (n = 20) except that 2 mg·kg-1 propofol iv was given instead of thiopental. The AAI, non-invasive blood pressure, and heart rate were measured every minute before induction for three minutes, at 1.5 min post-induction, and then each minute post-intubation for eight minutes.ResultsThe AAI increased significantly at one and two minutes after intubation in the thiopental group (to 56.5 ± 18.6 at 1 min and 44.7 ± 18.7 at 2 min after intubation vs 19.9 ± 7.5 at 1.5 min after induction; P < 0.05). Thereafter, AAI values gradually decreased three minutes after intubation. The AAI was inhibited continuously after intubation in the propofol group, and no significant elevation was seen.ConclusionOur results, using the AAI to monitor anesthetic depth during induction and tracheal intubation, suggest that at equipotent doses propofol provided a more stable level of anesthesia than did thiopental.RésuméObjectifLa modélisation autorégressive A-line avec index des potentiels évoqués (AAI) est une nouvelle méthode ďévaluation de la profondeur ďanesthésie. Nous avons vérifié les effets de ľintubation endotrachéale sur ľAAI et ľhémodynamique pendant ľinduction de ľanesthésie au propofol ou au thiopental chez des patients de plus de 50 ans.MéthodeQuarante patients, ďétat physique ASA I ou II et de plus de 50 ans, devant subir une laminectomie, une arthrodèse vertébrale postérieure, une vertébroplastie ou une arthroplastie totale de la hanche, ont été divisés au hasard en deux groupes. On a utilisé: 5 mg·kg-1 iv de thiopental, 2,5 μg·kg-1 de fentanyl iv et 0,7 mg·kg-1 iv de rocuronium dans le groupe thiopental (n = 20) pour ľinduction de ľanesthésie; le même protocole a été utilisé dans le groupe propofol (n = 20) sauf que 2 mg·kg-1 de propofol iv ont remplacé le thiopental. ĽAAI, la tension artérielle par mesure non effractive et la fréquence cardiaque ont été notés toutes les minutes avant ľinduction pendant trois minutes, à 1,5 min après ľinduction et à chaque minute après ľintubation pour huit minutes.RésultatsĽAAI s’est élevé significativement à une et deux minutes après ľintubation avec le thiopental (56,5 ± 18,6 à 1 min et 44,7 ± 18,7 à 2 min après ľintubation vs 19,9 ± 7,5 à 1,5 min après ľinduction, P < 0,05). Puis, les valeurs de ľAAI ont graduellement diminué trois minutes après ľintubation. ĽAAI a été inhibé de façon continue après ľintubation dans le groupe propofol et aucune élévation significative n’a été signalée.ConclusionAvec ľusage de ľAAI pour évaluer la profondeur de ľanesthésie pendant ľinduction et ľintubation endotrachéale, nous avons constaté qu’à doses équivalentes, le propofol fournit un niveau ďanesthésie plus stable que le thiopental.

Inadvertent Hypothermia Causes Pulseless Electrical Activity in a Patient during Cervical Spine Surgery- A Case Report

Recent studies have shown that hypothermia triples the incidence of major cardiac events. We present a happening in which a 71-year-old patient developed pulseless electrical activity (PEA) while he was undergoing cervical laminectomy for spinal stenosis in the sitting position. Thromboembolism or venous air embolism and acute myocardial infarction were respectively excluded by transesophageal echocardiography and cardiac enzymes analysis to be the causes of the cardiac event. The abnormal finding that stood out was low nasopharyngeal temperature (31 degrees C) during the procedure, which was thought to contribute to the development of the PEA episode.

Modulation of Propofol on the Effects of Blood Pressure and Firing Activity of Related Neurons in the Medulla

Many studies have demonstrated that the ventrolateral medulla (VLM) plays an important role in the maintenance of systemic arterial pressure (SAP) and vascular tone. The VLM is divided into rostral (RVLM) and caudal (CVLM) portions which play opposing roles in regulating cardiovascular functions. The purposes of this study are to explore the relationship of fibers projecting between the RVLM and CVLM, and to investigate the effect of propofol (PPF, 2 mg/kg), an anesthetic agent, on modulating their neuronal firing rate (NFR). Forty-four adult cats were anaesthetized intraperitoneally with urethane (400 mg/kg) and alpha-chloralose (40 mg/kg). The femoral artery was cannulated to allow monitoring of SAP and heart rate (HR). The femoral vein was cannulated for intravenous drug administration. Microinjection of glutamate (Glu, 3.0 nmol/30 nl), kynurenic acid (Kyn, 3.0 nmol/30 nl), gamma-aminobutyric acid (GABA, 4.0 nmol/30 nl), or bicuculline (Bicu, 4.0 nmol/30 nl) into the RVLM produced SAP increases or decreases, but did not significantly change the NFR in the CVLM. This occurred even after intravenous administration of PPF. This shows that there are few fiber projections from the RVLM to the CVLM. Conversely, microinjection of Glu, Kyn, GABA or Bicu into the CVLM produced SAP changes, and the NFR in the RVLM was significantly changed. These changes were more significant after intravenous administration of PPF. These results show that there are more fibers projecting from the CVLM to the RVLM and fewer fibers projecting from the RVLM to the CVLM to affect the SAP and its NFR.

Pneumopericardium after Bronchoscopic Carbon Dioxide Laser Surgery-A Case Report

A female baby sustained pneumopericardium after bronchoscopic CO2 laser surgery for tracheal stenosis. Perioperative pneumopericardium though rare is a life-threatening condition in babies. The symptoms are usually not specific such as hypotension, bradycardia, muffled heart sound, cardiovascular collapse, etc. The causes and clinical findings of pneumopericardium were reviewed, as are the radiographic features so as to differentiate the condition from pneumomediastinum. Early recognition of pneumopericardium is important, because emergent pericardiocentesis may be required if there is clinical evidence of cardiac tamponade.