Intrathecal injections of angiotensin IV and oxytocin conjugates induce antihyperalgesia and antiallodynia in both sexes of rats

Our previous studies have established that intrathecal oxytocin (OT) and angiotensin IV (Ang IV) injections induce antihyperalgesia and antiallodynia in rodents. Ang IV, a renin-angiotensin system hexapeptide, acts as an endogenous inhibitor that inhibits the oxytocin-degrading enzyme insulin-regulated aminopeptidase (IRAP). The pain inhibitory effects by Ang IV were found to be through its inhibition on IRAP to potentiate the effect of OT. However, these effects were found to be with a significant sex difference, which could be partially due to the higher expression of IRAP at the spinal cords of female. Therefore, we synthesized Ang IV and OT conjugates connected with a peptide bond and tested for their effects on hyperalgesia and allodynia. Carrageenan-induced hyperalgesia and partial sciatic nerve ligation (PSNL) were performed using rat models. Conjugates Ang IV-OT (Ang IV at the N-terminal) and OT-Ang IV (OT at the N-terminal) were synthesized and intrathecally injected into male and female rats. Our results showed that Ang IV-OT exhibited prominent antihyperalgesia in male rats, particularly during hyperalgesia recovery, whereas OT-Ang IV was more effective during development stage. Ang IV-OT showed clear antihyperalgesia in female rats, but OT-Ang IV had no significant effect. Notably, both conjugates alleviated neuropathic allodynia in male rats; however, OT-Ang IV had no effect in female rats, whereas Ang IV-OT induced significant antiallodynia. In conclusion, Ang IV-OT has greater therapeutic potential for treating hyperalgesia and allodynia than OT-Ang IV. Its effects were not affected by sex, unlike those of OT and OT-Ang IV, extending its possible clinical applications.

Decreasing the incidence of central line-associated bloodstream infection in a medical intensive care unit: a best practice implementation project

INTRODUCTION AND OBJECTIVES

Bloodstream infections are common in critically ill patients using central venous access devices (CVAD) in intensive care units (ICU). This project aimed to decrease the incidence of central line-associated bloodstream infections (CLABSI) by using evidence-based strategies.

METHODS

The project applied the JBI audit and feedback methods. Thirty-two nurses and five resident physicians from the medical ICU of a medical center participated in the project. Preintervention compliance was measured for the 11 key evidence-based criteria (six audit criteria of central venous catheter insertion and five audit criteria of dressing and catheter securement). Strategies were implemented to overcome the barriers identified in the baseline assessment. Impact evaluation and sustainability were conducted to change the CLABSI rate and the competence of healthcare professionals in providing CVAD care. The JBI Practical Application of Clinical Evidence System and Getting Research into Practice audit tools were used for the data collection, analysis, and implementation planning.

RESULTS

Barriers included insufficient knowledge among nurses and physicians, poor compliance with the standard CVAD insertion procedure by physicians, inadequate cooperation among the CVAD care team members, and lack of CVAD-related equipment. The strategies included education and training in CVAD care, the establishment of a team resource management program, and the provision of appropriate equipment. Following project implementation, the CLABSI rate decreased from 8.38 to 3.9 BSIs/1000 CVAD-days.

CONCLUSIONS

The project successfully decreased the CLABSI rate and increased the competence of healthcare professionals. Implementation of best practices in clinical care should focus on leadership, team resource management, education, monitoring, and innovation.

Effects of dextromethorphan on nicotine-induced reward, behavioral sensitization, withdrawal signs, and drug seeking-related behavior in rats

Introduction

Tobacco products are addictive, with nicotine serving as the major addictive ingredient. Chronic tobacco use or chronic administration of nicotine alone results in both physiological and psychological dependence. Our previous studies indicated that dextromethorphan (DM) could effectively attenuate dependence of morphine and methamphetamine. Thus, we further investigated the possible effects of DM on nicotine dependence.

Methods

Conditioned place preference (CPP) test was used to examine nicotine-induced rewarding effects as well as the drug-seeking related behavior in rats. Nicotine dependence was induced by continuous subcutaneous infusion of nicotine via an osmotic minipump for 7 days and abstinence was initiated by removal of the pump. Withdrawal signs were observed and quantified. Locomotor activity was measured to determine the behavioral sensitization induced by nicotine. To investigate the activity of mesolimbic dopaminergic neuronal activity in correlation with the effects of nicotine, the animals were sacrificed and the nucleus accumbens (NAc), dorsal striatum (DS) and medial prefrontal cortex (mPFC) were dissected and used to determine the contents of dopamine and its metabolites by HPLC.

Results

Our results showed that DM could suppress nicotine-induced rewarding effect and drug seeking-related behavior. In addition, co-administration and post-treatment of DM could both attenuate nicotine withdrawal signs. Moreover, DM could suppress nicotine-induced behavioral sensitization. In neurochemical experiments, co-administration and post-treatment of DM abolished nicotine-induced increase of the DA turnover rate in the mPFC, but not in the NAc and DS.

Conclusions

These results suggest that DM have a great therapeutic potential in the treatment of nicotine dependence.

Implications

Our results showed that dextromethorphan could suppress nicotine-induced rewarding effect and drug seeking-related behaviour. In addition, co-administration and post-treatment of dextromethorphan could both attenuate nicotine withdrawal signs. Moreover, dextromethorphan could suppress nicotine-induced behavioural sensitization. In neurochemical experiments, co-administration and post-treatment of dextromethorphan abolished nicotine-induced increase of the dopamine turnover rate in the medial prefrontal cortex, but not in the nucleus accumbens and dorsal striatum. These results suggest that dextromethorphan have a great therapeutic potential in the treatment of nicotine dependence.

Case report: the management for a gestational hypertensive woman with influenza A virus pneumonia and peripartum cardiomyopathy

Background

Peripartum cardiomyopathy (PPCM) is defined as an idiopathic cardiomyopathy occurring in the last month of pregnancy or the first 6 months postpartum without an identifiable cause. PPCM is suspected to be triggered by the generation of a cardiotoxic fragment of prolactin and the secretion of a potent antiangiogenic protein from the placental, but no single factor has been identified or defined as the underlying cause of the disease. Influenza virus can cause PPCM through immune-mediated response induced by proinflammatory cytokines from host immunity and endothelial cell dysfunction. We report a case in a parturient woman undergoing a cesarean delivery, who had influenza A pneumonia and PPCM.

Case presentation

A parturient woman at 40 weeks and 1 day of gestation who had experienced gestational hypertension accompanied by pulmonary edema developed hypotension after undergoing an emergency cesarean delivery. An elevation of N-terminal prohormone of brain natriuretic peptide (NT-proBNP) was noted, and echocardiography revealed a left ventricular ejection fraction of 20%. She underwent a nasopharyngeal swab test, in which influenza A antigen was positive. She was diagnosed as having PPCM and received anti-viral treatment. After antiviral treatment, hemodynamic dysfunction stabilized. We present and discuss the details of this event.

Conclusion

PPCM is a heart disease that is often overlooked by medical personnel. Rapid swab tests, serum creatine kinase measurement, and echocardiography are imperative diagnostic approaches for the timely recognition of virus-associated cardiomyopathy in peripartum women with influenza-like disease and worsening dyspnea, especially during the epidemic season. Prompt antiviral treatment should be considered, particularly after PPCM is diagnosed.

Supplementary information

The online version contains supplementary material available at 10.1186/s12884-022-04814-9.

Implementing a flipped classroom model in an evidence-based medicine curriculum for pre-clinical medical students: evaluating learning effectiveness through prospective propensity score-matched cohorts

BACKGROUND

In a flipped classroom (FC) model, blended learning is used to increase student engagement and learning by having students finish their readings at home and work on problem-solving with tutors during class time. Evidence-based medicine (EBM) integrates clinical experience and patient values with the best evidence-based research to inform clinical decisions. To implement a FC and EBM, students require sufficient information acquisition and problem-solving skills. Therefore, a FC is regarded as an excellent teaching model for tutoring EBM skills. However, the effectiveness of a FC for teaching EBM competency has not been rigorously investigated in pre-clinical educational programs. In this study, we used an innovative FC model in a pre-clinical EBM teaching program.

METHODS

FC's teaching was compared with a traditional teaching model by using an assessment framework of prospective propensity score matching, which reduced the potential difference in basic characteristics between the two groups of students on 1:1 ratio. For the outcome assessments of EBM competency, we used an analysis of covariance and multivariate linear regression analysis to investigate comparative effectiveness between the two teaching models. A total of 90 students were prospectively enrolled and assigned to the experimental or control group using 1:1 propensity matching.

RESULTS

Compared with traditional teaching methods, the FC model was associated with better learning outcomes for the EBM competency categories of Ask, Acquire, Appraise, and Apply for both written and oral tests at the end of the course (all p-values< 0.001). In particular, the "appraise" skill for the written test (6.87 ± 2.20) vs. (1.47 ± 1.74), p < 0.001), and the "apply" skill for the oral test (7.34 ± 0.80 vs. 3.97 ± 1.24, p < 0.001) had the biggest difference between the two groups.

CONCLUSIONS

After adjusting for a number of potential confunding factors, our study findings support the effectiveness of applying an FC teaching model to cultivate medical students' EBM literacy.

Estrogen can abolish oxytocin-induced spinal anti-hyperalgesia

Our previous study verified a sex difference of anti-hyperalgesia in rats and anti-allodynia in mice induced by intrathecal oxytocin (OT). In the model of intraplantar carrageenan-induced inflammatory hyperalgesia, intrathecal OT injection induced a substantial anti-hyperalgesia in male rats even at a low dose (0.125 nmol). In contrast, female rats only responded to an extremely high dose (1.25 nmol). This sex difference concurs with a lower expression of OT receptors and higher expression of insulin-regulated aminopeptidase (IRAP; OT degrading enzyme) in the spinal cords of female rats. In this study, we further determined the role of female hormones in this sex difference by using ovariectomized rats. Our results show that a low dose of intrathecal OT caused a significant anti-hyperalgesia effect in ovariectomized female rats, similar to that seen in male rats. Ovariectomy did not cause any change of paw edema except at the late stage of convalescence when compared with the sham-operated group. Ovariectomy-induced faster recovery from edema but did not affect the severity of hyperalgesia. Moreover, there was a similar amount of IRAP expression in ovariectomized and sham rats. When estradiol (E2) was given together with OT, OT-induced anti-hyperalgesia was abolished at the developmental stage of hyperalgesia in ovariectomized rats. These results show an inhibitory role of female hormones generated from ovaries (mainly estrogen) in the sex difference of anti-hyperalgesia induced by OT. This study suggests the feasibility of a novel OT-based remedy to treat hyperalgesia in men and in menopausal women no receiving hormonal supplements.

Patients with alcohol use disorder increase pain and analgesics use: A nationwide population-based cohort study

BACKGROUND

Alcohol has dual effects on many systems, including the pain system. We will test whether and how chronic alcohol consumption enhances pain sensation to develop pain disorder.

METHODS

We conducted a retrospective matched cohort study using data from the National Health Insurance Research Database (NHIRD) in Taiwan, in patients with and without alcohol use disorder (AUD). This study enrolled 19,174 individuals with AUD as study cohort and 19,174 propensity score-matched individuals without AUD as comparison cohort. The outcome was the incidence of pain disorders and the need for analgesics. The hazard ratios of pain disorders and the need for analgesics were evaluated using Cox proportional hazard regression analysis after adjusting for age, sex, index year, comorbidities, urbanization, areas of residence, and insurance premium.

RESULTS

The 14 years of follow-up showed that AUD patients had a higher adjusted hazard ratio (aHR) for developing pain disorders than in non-AUD controls [aHR= 1.290, 95% confidence interval (CI): 1.045-1.591]. Besides, AUD patients had a higher risk of analgesic use (aHR = 1.081, 95% CI: 1.064-1.312), including opioids and non-opioid analgesics. Most importantly, AUD patients required more days of analgesic use, increased dose of analgesics, and higher costs of analgesics. Moreover, AUD patients had more anemia (aHR=2.772, 95% CI: 2.581-2.872), which could be a mediating factor.

CONCLUSIONS

AUD patients had higher risks of developing pain disorders and subsequently increased analgesic demand. These results suggest that AUD worsened pain, and pain syndrome is correlated with the duration of chronic alcohol exposure.

Effectiveness of Music-Based Intervention in Improving Uncomfortable Symptoms in ICU Patients: An Umbrella Review

Background: Intensive care unit (ICU) patients experience multiple uncomfortable symptoms, which may be alleviated using music-based intervention, a nondrug treatment. This umbrella review aims to combine the data of systematic reviews and/or meta-analyses to evaluate the effectiveness of music-based intervention in improving uncomfortable symptoms in ICU patients. Methods: A comprehensive literature search was performed on the PubMed, Embase, Cochrane Library, Airiti Library, CINAHL, ProQuest, and Web of Science databases, and Epistemonikos. The search had no language restrictions, and articles on the improvement of symptoms using music-based intervention in adult ICU patients were included. This review protocol was registered on PROSPERO (CRD42021240327). Results: This umbrella review retrieved 5 systematic reviews and 41 original studies, including 39 randomized controlled trials, and 2 nonrandomized controlled trials. Diverse music was the most common music type used for music-based intervention, the intervention music was typically decided by the study participants (61%), and most subjects underwent one intervention session (78%). Furthermore, most music intervention sessions lasted for 30 min (44%). The positive results included decreased anxiety, decreased pain, decreased agitation, decreased anesthesia dose and sedative use, decreased chances of delirium, decreased feelings of uncomfort, and improved sleep quality. Conclusions: A systematic review on the effectiveness of music-based intervention in improving uncomfortable symptoms in ICU patients revealed that 20–30 min intervention sessions showed the best improvement in the uncomfortable symptoms in patients. This study provides a basis for using music-based intervention to relieve the uncomfortable symptoms in critically ill ICU patients, and a reference for empirical clinical practice.

LVV-hemorphin-7 (LVV-H7) plays a role in antinociception in a rat model of alcohol-induced pain disorders

Alcohol can increase the sensitivity to painful stimulation or convert insensibility to pain at different stages. We hypothesized that chronic alcohol consumption changes the level of LVV-hemorphin-7 (abbreviated as LVV-H7, an opioid-like peptide generated from hemoglobin β-chain), thereby affecting pain sensation. We established a chronic alcohol-exposed rat model to investigate the effects of LVV-H7. Adult male Sprague-Dawley rats were subjected to daily intraperitoneal injection of 10 % ethanol (w/v) at 0.5 g/kg for 15 days and subsequent alcohol withdrawal for 5 days. Using different pharmacological strategies to affect the LVV-H7 level, we investigated the correlation between LVV-H7 and pain-related behavior. Tail-flick and hot plate tests were employed to investigate alcohol-induced pain-related behavioral changes. The serum level of LVV-H7 was determined by ELISA. Our results showed that alcohol first induced an analgesia followed by a hyperalgesia during alcohol withdrawal, which could be driven by the quantitative change of LVV-H7. A positive correlation between the level of LVV-H7 and Δtail-flick latency (measured latency minus basal latency) confirmed this finding. Moreover, we revealed that the LVV-H7 levels were determined by the activity of cathepsin D and red blood cell/hemoglobin counts, which could be affected by alcohol. These results suggest that the deterioration of anti-nociception induced by alcohol is correlated to the decreased level of LVV-H7, and this could be due to alcohol-induced anemia. This study may help to develop LVV-H7 structure-based novel analgesics for treating alcohol-induced pain disorders and thus ameliorate the complications in alcoholics.

Salivary cortisol is associated with cognitive changes in patients with fibromyalgia

Fibromyalgia (FM) is a stress-related chronic pain disorder with common cognitive complaints. This study characterized cognitive dysfunction in patients with FM and explored whether these changes are linked to altered cortisol levels. Consecutive 44 patients with FM and 48 healthy controls were enrolled for the assessments of subjective and objective cognitive functions and diurnal levels of salivary cortisol (sampled at awakening, 30 min after awakening, 3 pm, and bedtime). All measurements were compared between the groups and evaluated for clinical correlation. The FM group had more subjective cognitive complaints and performed poorer in objective cognitive testing in memory (delayed recall in Chinese Version Verbal Learning Test and Taylor Complex Figure Test), language (Boston Naming Test), and executive domains (Wisconsin Card Sorting Test) after adjustments for education. The diurnal cortisol levels of patients with FM tended to be lower, especially at 30 min after awakening and bedtime. Moreover, moderate positive correlations existed between the Chinese Version Verbal Learning Test, Boston Naming Test and the morning cortisol levels within the FM group. We suggested the altered cognitive function in FM may be linked to stress maladaptation. Future studies are warranted to elucidate whether stress management improves cognitive performance in patients with FM.

Sex Difference of Angiotensin IV-, LVV-Hemorphin 7-, and Oxytocin-Induced Antiallodynia at the Spinal Level in Mice With Neuropathic Pain

BACKGROUND

We demonstrated previously that angiotensin IV (Ang IV) and LVV-hemorphin 7 (LVV-H7) act through the blockade of insulin-regulated aminopeptidase to decrease oxytocin degradation, thereby causing antihyperalgesia at the spinal level in rats. We determined that intrathecal oxytocin can induce significant antihyperalgesia in male rats with inflammation but not in female rats. Thus, we speculate that Ang IV, LVV-H7, and oxytocin can induce antiallodynia, which could be of great therapeutic potential. Because the antihyperalgesia by using these peptides was with sex difference, their possible antiallodynia was examined in male and female mice for comparison. We investigated whether Ang IV, LVV-H7, and oxytocin produce antiallodynia at the spinal level in mice and whether this antiallodynia differs between the sexes.

METHODS

Partial sciatic nerve ligation surgery was performed on adult male and female C57BL/6 mice from the same litter (25-30 g). The effects of intrathecal injections of Ang IV (25.8 nmol), LVV-H7 (27.2 nmol), and oxytocin (0.125 or 1.25 nmol) were assessed through the von Frey test 3 days after partial sciatic nerve ligation.

RESULTS

Intrathecal injection of Ang IV, LVV-H7, and oxytocin all produced a potent antiallodynia in male mice. However, these antiallodynia effects were either extremely weak or absent in female mice at the same dose.

CONCLUSIONS

Intrathecal Ang IV, LVV-H7, and oxytocin can all cause significant antiallodynia in male mice. The Ang IV-, LVV-H7-, and oxytocin-induced antiallodynia effects differed between the sexes at the spinal level in mice.

Chronic administration of nandrolone increases susceptibility to morphine dependence without correlation with LVV-hemorphin 7 in rats

LVV-hemorphin 7 (LVVYPWTQRF; LVV-H7), an N-terminal fragment of the β-chain of hemoglobin cleaved by cathepsin D/pepsin, is an atypical endogenous opioid peptide that is found in high concentration in blood. LVV-H7 acts as a μ-opioid agonist and an inhibitor of insulin-regulated aminopeptidase. Subchronic administration of anabolic androgenic steroids (AAS) has been clinically proven to induce the synthesis of erythrocytes and increase hemoglobin concentrations. Patients with a history of AAS abuse are more susceptible to opioid abuse. We hypothesized that this association could be at least partially attributed to the sensitization of the mesocorticolimbic dopaminergic pathway by LVV-H7. Using the conditioned place preference test and neurochemical analysis, we investigated the possible mechanism underlying the effect of chronic nandrolone administration on morphine-induced reward and its correlation with LVV-H7 in rats. Either LVV-H7 may not sensitize the rewarding neural circuits or its inhibition on locomotor activity could mask reward-related behaviors. Chronic nandrolone pretreatment indeed caused a significant reward by low dose morphine, which did not cause any reward in control rats. However, coadministration of anti-LVV-H7 antiserum with nandrolone did not block this effect. This may rule out the possibility of the involvement of LVV-H7 in the action of nandrolone to intensify morphine-induced reward. Moreover, the serum level of LVV-H7 was mildly increased in response to chronic nandrolone administration in our animal model. According to the current clinical observations, we may conclude that the chronic administration of nandrolone can increase susceptibility to morphine dependence, but that this effect is not related to elevated LVV-H7.

Sex Difference in Oxytocin-Induced Anti-Hyperalgesia at the Spinal Level in Rats with Intraplantar Carrageenan-Induced Inflammation

Previously, we demonstrated intrathecal administration of oxytocin strongly induced anti-hyperalgesia in male rats. By using an oxytocin-receptor antagonist (atosiban), the descending oxytocinergic pathway was found to regulate inflammatory hyperalgesia in our previous study using male rats. The activity of this neural pathway is elevated during hyperalgesia, but whether this effect differs in a sex-dependent manner remains unknown. We conducted plantar tests on adult male and female virgin rats in which paw inflammation was induced using carrageenan. Exogenous (i.t.) application of oxytocin exerted no anti-hyperalgesic effect in female rats, except at an extremely high dose. Female rats exhibited similar extent of hyperalgesia to male rats did when the animals received the same dose of carrageenan. When atosiban was administered alone, the severity of hyperalgesia was not increased in female rats. Moreover, insulin-regulated aminopeptidase (IRAP) was expressed at higher levels in the spinal cords of female rats compared with those of male rats. Oxytocin-induced anti-hyperalgesia exhibits a sex-dependent difference in rats. This difference can partially result from the higher expression of IRAP in the spinal cords of female rats, because IRAP functions as an enzyme that degrades oxytocin. Our study confirms the existence of a sex difference in oxytocin-induced anti-hyperalgesia at the spinal level in rats.

Angiotensin IV possibly acts through PKMzeta in the hippocampus to regulate cognitive memory in rats

Ang IV is an endogenous peptide generated from the degradation of angiotensin II. Ang IV was found to enhance learning and memory in CNS. PKMzeta was identified to be a fragment of PKCzeta (protein kinase Czeta). Its continuous activation was demonstrated to be correlated with the formation of memory in the hippocampus. Therefore, we investigated whether PKMzeta participates in the effects of Ang IV on memory. We first examined the effect of Ang IV on non-spatial memory/cognition in modified object recognition test in rats. Our data showed that Ang IV could increase the exploration time on novel object. The co-administration of ZIP (PKMzeta inhibitor) with Ang IV significantly blocked the effect by Ang IV. The effects of Ang IV on hippocampal LTP at the CA1 region were also evaluated. Ang IV significantly increased the amplitude and slope of the EPSPs, which was consistent with other reports. Surprisingly, instead of potentiating LTP, Ang IV caused a failed maintenance of LTP. Moreover, there was no quantitative change in PKMzeta induced by Ang IV and/or ZIP after behavioral experiments. Taken together, our data re-confirmed the finding of the positive effect of Ang IV to enhance memory/cognition. The increased strength of EPSPs with Ang IV could also have certain functional relevance. Since the behavioral results suggested the involvement of PKMzeta, we hypothesized that the enhancement of memory/cognition by Ang IV may rely on an increase in PKMzeta activity. Overall, the present study provided important advances in our understanding of the action of Ang IV in the hippocampus.

The Effects of Anti-Dementia and Nootropic Treatments on the Mortality of Patients with Dementia: A Population-Based Cohort Study in Taiwan

Background

Few studies have examined the contribution of treatment on the mortality of dementia based on a population-based study.

Objective

To investigate the effects of anti-dementia and nootropic treatments on the mortality of dementia using a population-based cohort study.

Methods

12,193 incident dementia patients were found from 2000 to 2010. Their data were compared with 12,193 age- and sex-matched non-dementia controls that were randomly selected from the same database. Dementia was classified into vascular (VaD) and degenerative dementia. Mortality incidence and hazard ratios (HRs) were calculated.

Results

The median survival time was 3.39 years (95% confidence interval [CI]: 2.88–3.79) for VaD without medication, 6.62 years (95% CI: 6.24–7.21) for VaD with nootropics, 3.01 years (95% CI: 2.85–3.21) for degenerative dementia without medication, 8.11 years (95% CI: 6.30–8.55) for degenerative dementia with anti-dementia medication, 6.00 years (95% CI: 5.73–6.17) for degenerative dementia with nootropics, and 9.03 years (95% CI: 8.02–9.87) for degenerative dementia with both anti-dementia and nootropic medications. Compared to the non-dementia group, the HRs among individuals with degenerative dementia were 2.69 (95% CI: 2.55–2.83) without medication, 1.46 (95% CI: 1.39–1.54) with nootropics, 1.05 (95% CI: 0.82–1.34) with anti-dementia medication, and 0.92 (95% CI: 0.80–1.05) with both nootropic and anti-dementia medications. VaD with nootropics had a lower mortality (HR: 1.25, 95% CI: 1.15–1.37) than VaD without medication (HR: 2.46, 95% CI: 2.22–2.72).

Conclusion

Pharmacological treatments have beneficial effects for patients with dementia in prolonging their survival.

Dextromethorphan potentiates morphine antinociception at the spinal level in rats

PURPOSE

Morphine is an effective analgesic, but adverse effects limit its clinical use in higher doses. The non-opioid antitussive, dextromethorphan (DM), can potentiate the analgesic effect of morphine and decrease the dose of morphine in acute postoperative pain, but the underlying mechanism remains unclear. We previously observed that DM increases the serum concentration of morphine in rats. Therefore, we investigated the effects of drugs administered at the spinal level to exclude possible pharmacokinetic interactions. As DM has widespread binding sites in the central nervous system [such as N-methyl-D-aspartate (NMDA) receptors, sigma receptors and alpha(3)ss(4) nicotinic receptors], we investigated whether the potentiation of morphine antinociception by DM at the spinal level is related to NMDA receptors.

METHODS

We used MK-801 as a tool to block the NMDA channel first, and then studied the interaction between intrathecal (i.t.) morphine and DM. The tail-flick test was used to examine the antinociceptive effects of different combinations of morphine and other drugs in rats.

RESULTS

DM (2-20 microg) or MK-801 (5-15 microg) showed no significant antinociceptive effect by themselves. The antinociceptive effect of morphine (0.5 microg, i.t.) was significantly enhanced by DM and reached the maximal potentiation (43.7%-50.4%) at doses of 2 to 10 microg. Pretreatment with MK-801 (5 or 10 microg, i.t.) significantly potentiated morphine antinociception by 49.9% or 38.7%, respectively. When rats were pretreated with MK-801, DM could not further enhance morphine antinociception (45.7% vs 50.5% and 43.3%).

CONCLUSION

Our results suggest that spinal NMDA receptors play an important role in the effect of DM to potentiate morphine antinociception.

Successful anesthetic management of a patient with thyroid carcinoma invading the trachea with tracheal obstruction, scheduled for total thyroidectomy

We report a case of large thyroid carcinoma with tracheal and esophageal invasion who presented with preoperative stridor scheduled for total thyroidectomy and segmental tracheal resection. Careful and comprehensive preoperative anesthetic planning was done. Extracorporeal circulation membrane oxygenation (ECMO) was set up and running prior to induction under local anesthesia, due to an increased international normalized ratio (INR) and fear of bleeding in the airway. Fiberoptic bronchoscopy (FOB) is the first choice in many circumstances of difficult airway. However, we twice failed to intubate under FOB guidance. Successful intubation was done with traditional laryngoscopy and a Glidescope. The operative course was smooth. The oral endotracheal tube (ETT) was changed to a nasal ETT after surgery with the Glidescope. FOB-assisted intubation carries a chance of failure, and in critical patients, the presence of other intubating modalities such as video-assisted or fiberoptic-assisted technology or safety measures, including ECMO, will greatly increase the safety of anesthesia and surgery.

A possible correlation between oxytocin-induced and angiotensin IV-induced anti-hyperalgesia at the spinal level in rats

In our previous study, we showed that intrathecal (i.t.) administration of angiotensin IV (Ang IV), an insulin-regulated aminopeptidase (IRAP) inhibitor, attenuated inflammatory hyperalgesia in rats. Using the plantar test in rats with carrageenan-induced paw inflammation, we investigated the possible mechanism(s) of this effect. Because i.t. oxytocin was reported to produce a dose-dependent anti-hyperalgesia in rats with inflammation, we speculate that there is a possible correlation between oxytocin-induced and Ang IV-induced anti-hyperalgesia. Using i.t. co-administered atosiban (oxytocin receptor antagonist), the anti-hyperalgesia by Ang IV was completely abolished. This indicated that oxytocin could be the major IRAP substrate responsible for the anti-hyperalgesia by Ang IV. When Ang IV was co-administered with a low dose of oxytocin, there was a significant enhancing effect of Ang IV on oxytocin-induced anti-hyperalgesia. In recent reports, electrical stimulation on the paraventricular hypothalamic nucleus (PVN) was proved to increase oxytocin release at the spinal cord. Our results also showed that Ang IV could prolong the anti-hyperalgesia induced by PVN stimulation. This suggests a possible protective effect of Ang IV on endogenous oxytocin degradation/dysfunctioning. Moreover, we examined the local effect of intraplantarly injected Ang IV in the same model. Our results showed no effect of local Ang IV on hyperalgesia and paw edema, indicating that Ang IV may not regulate the peripheral inflammatory process. Overall, our study suggests that Ang IV may act through the inhibition of the activity of IRAP to reduce the degradation of oxytocin at the spinal cord, thereby leading to anti-hyperalgesia in rats with inflammation.

Difficult weaning from mechanical ventilator in a patient with corticosteroid insufficiency after low anterior resection of sigmoid colon

A 75-year-old man underwent low anterior resection for sigmoid colon cancer under general anesthesia. Comprehensive preoperative surveys showed normal cardiopulmonary functions. In spite of adequate fluid administration, persistent intraoperative hypotension required vasopressors to maintain an acceptable blood pressure. Although the patient was fully awakened from anesthesia with adequate oxygenation, repeated attempts to wean him from the ventilator failed in the postanesthesia intensive care unit, despite recovery from the effect of muscle relaxant. Low plasma cortisol level was found in a series of laboratory analyses. After supplementation with corticosteroid, the patient was successfully weaned from the mechanical ventilator without any sequelae.

Urinary catheterization may not be necessary in minor surgery under spinal anesthesia with long-acting local anesthetics

BACKGROUND

This prospective study was designed to compare the incidence of urinary retention after spinal anesthesia between 0.5% hyperbaric bupivacaine and 0.5% hyperbaric tetracaine in patients who underwent minor orthopedic and general surgeries.

METHODS

Eighty patients aged 18-40 were randomly assigned to receive either hyperbaric bupivacaine or tetracaine for spinal anesthesia. Intravenous fluids were administered for maintenance of basal requirement, replacement of blood loss and prevention of hypotension. The highest level of analgesia, regression time of sensory block to L5 level, length of time from spinal injection to spontaneous urinary voidance, and volume of perioperative fluid administered were recorded.

RESULTS

Of the 80 patients who received either hernioplasty, fistulectomy, hemorroidectomy or orthopedic surgery, two were catheterized (2.5%) because of urinary retention. They were administered less than 800 mL of fluid intraoperatively. Intraoperative blood loss was less than 100 mL in all cases. There were no statistical differences in demographic data, types of surgery, sensory blockade and perioperative fluid administration between the two groups. Although the regression time of sensory blockade with tetracaine (means +/- SD, 259.3 +/- 39.6 min) was significantly longer than that of bupivacaine (225.0 +/- 38.6 min, P < 0.01), the time elapsing from the spinal injection to the first spontaneously voiding after surgery did not show statistical difference between two groups (433.9 +/- 89.1 vs. 411.0 +/- 98.3 min, P = 0.286).

CONCLUSIONS

Our results show that, in younger surgical patients who did not receive large amount of fluid intraoperatively, the incidence of urinary retention was low, although prolonged sensory blockade by both long-acting local anesthetics was evident. Thus, urinary catheterization should not be a routine must for every patient undergoing minor surgery with long-acting spinal local anesthetics. From the viewpoint of financial expense, avoidance of complication and annoyance of urinary catheterization, careful observation of urinary bladder fullness in the form of lower abdominal distension, discomfort, bradycardia, or vomiting after surgery is superior to routine retention urinary catheterization just for ease with work in younger patients under-going minor surgery under long-acting spinal local anesthetics.

Dextromethorphan differentially affects opioid antinociception in rats

Opioid drugs such as morphine and meperidine are widely used in clinical pain management, although they can cause some adverse effects. A number of studies indicate that N-methyl-D-aspartate (NMDA) receptors may play a role in the mechanism of morphine analgesia, tolerance and dependence. Being an antitussive with NMDA antagonist properties, dextromethorphan (DM) may have some therapeutic benefits when coadministered with morphine. In the present study, we investigated the effects of DM on the antinociceptive effects of different opioids. We also investigated the possible pharmacokinetic mechanisms involved. The antinociceptive effects of the mu-opioid receptor agonists morphine (5 mg kg(-1), s.c.), meperidine (25 mg kg(-1), s.c.) and codeine (25 mg kg(-1), s.c.), and the kappa-opioid agonists nalbuphine (8 mg kg(-1), s.c.) and U-50,488H (20 mg kg(-1), s.c.) were studied using the tail-flick test in male Sprague-Dawley rats. Coadministration of DM (20 mg kg(-1), i.p.) with these opioids was also performed and investigated. The pharmacokinetic effects of DM on morphine and codeine were examined, and the free concentration of morphine or codeine in serum was determined by HPLC.It was found that DM potentiated the antinociceptive effects of some mu-opioid agonists but not codeine or kappa-opioid agonists in rats. DM potentiated morphine's antinociceptive effect, and acutely increased the serum concentration of morphine. In contrast, DM attenuated the antinociceptive effect of codeine and decreased the serum concentration of its active metabolite (morphine). The pharmacokinetic interactions between DM and opioids may partially explain the differential effects of DM on the antinociception caused by opioids.

Effects of morphine and endomorphins on the polysynaptic reflex in the isolated rat spinal cord

At the spinal level, mu-opioids exert their actions on nociceptive primary afferent neurons both pre- and postsynaptically. In the present study, we used an in vitro isolated neonatal rat (11-15 days old) spinal cord preparation to examine the effects of morphine and the endogenous mu-opioid ligands endomorphin-1 (EM-1) and endomorphin-2 (EM-2) on the polysynaptic reflex (PSR) of dorsal root-ventral root (DR-VR) reflex. The actions of mu-opioids on spinal nociception were investigated by quantification of the firing frequency and the mean amplitude of the PSR evoked by stimuli with 20 x threshold intensity. EM-1 decreased the mean amplitude of PSR, whereas EM-2 and morphine decreased the firing frequency. The pattern of the effects elicited by morphine was the same as that for EM-2, except at high concentration. Naloxonazine, a selective mu(1) opioid receptor antagonist, had no significant effect on PSR by itself, but blocked the inhibition of PSR firing frequency or amplitude induced by EM-1, -2 and morphine. This may suggest that EM-1, EM-2 and morphine modulate spinal nociception differently and act mainly at the mu(1)-opioid receptors. Although they all act via mu(1)-opioid receptors, their different effects on the PSR may suggest the existence of different subtypes of the mu(1)-opioid receptor. The present data is also consistent with a further hypothesis, namely, that morphine and EM-2 activate a subtype of mu(1)-opioid receptor presynaptically, while EM-1 acts mainly through another subtype postsynaptically. However, since other reports indicate that EM-2, but not EM-1, could stimulate the release of enkephalins or dynorphin, presynaptic delta and kappa receptors may be also involved indirectly in the different regulation by mu-opioids at the spinal level.

Dextromethorphan potentiates morphine-induced antinociception at both spinal and supraspinal sites but is not related to the descending serotoninergic or adrenergic pathways

Morphine is a strong and widely used opioid analgesic in pain management, but some adverse effects limit its clinical use at high doses. The clinically available non-opioid antitussive, dextromethorphan (DM) can potentiate the analgesic effect of morphine and decrease the dose of morphine in acute postoperative pain. However, the mechanism underlying this synergistic phenomenon is still not clear. To examine if the potentiation by DM occurs through the descending pain-inhibitory pathways, ketanserin (a 5-HT2 receptor antagonist) and yohimbine (an alpha2-adrenergic receptor antagonist) were employed and found to have no significant effect on the potentiation by DM. Using local delivery of drugs in rats in the present study, potentiation of morphine-induced antinociception by DM was observed via both intrathecal and intracerebroventricular routes, suggesting that both spinal and supraspinal sites are involved. This suggests that the potentiation of morphine-induced antinociception by DM is not mediated by the serotoninergic or adrenergic descending pain-inhibitory pathways. The present results are consistent with findings in clinical studies, which showed that DM can effectively decrease the consumption of morphine in patients suffering from pain. Since DM has excellent clinical potential as a synergistic agent with morphine, further investigating and clarifying the possible pharmacological mechanism of DM are of great importance for future studies.

Fatal Gas Embolism During Transurethral Incision of the Bladder Neck Under Spinal Anesthesia

We report a case of fatal gas embolism during transurethral incision of the bladder neck under spinal anesthesia in a 76-yr-old man. We confirmed the diagnosis of venous gas embolism by aspiration of frothy blood through the double-lumen central venous catheter and by observation on the transesophageal echocardiogram of a massive gas embolism in the right atrium and right ventricle with obstruction of right ventricle outflow. This report is presented in an attempt to remind anesthesiologists of this unusual but potentially fatal complication that may occur during common transurethral surgery.

IMPLICATIONS

We report a patient undergoing transurethral incision of the bladder neck who developed a fatal gas embolism. This report is presented in an attempt to remind anesthesiologists of this unusual but potentially fatal complication that may occur during common transurethral surgery.

Oral clonidine reduces myocardial ischemia in patients with coronary artery disease undergoing noncardiac surgery

BACKGROUND

To access the clinical effect of clonidine on reduction of myocardial ischemia events in patients with history of coronary artery disease undergoing noncardiac surgeries.

METHODS

Sixty ASA class III patients with coronary artery disease were allotted at random to two groups in a prospective, double-blind study to receive either clonidine (3 micrograms/kg) or placebo (control group) 90 minutes before arrival at the operating room. Continuous EKG monitoring (Holter monitor) was performed to analyze the ST segment in lead II, V2 and V5 during the preoperative (since late hours the night before operation), intraoperative and early postoperative periods (total monitoring time = 24 hours). The episode of myocardial ischemia defined as the magnitude of ST segment depression of at least 1 mm, occurring 60 ms after the J point and persisting for three minutes or more was recorded. Perioperative hemodynamic data were analyzed with two-way ANOVA with repeated measures. Student's t-test for unpaired data was used for analysis of demographics. Chi-square test was used for ST segment changes. Results are expressed as mean +/- SD and P < 0.05 was considered to be statistically significant.

RESULTS

In the control group, 9 patients (30%) were noted to have episodes of ischemia preoperatively, 7 patients (23.3%) intraoperatively, and 12 patients (40%) postoperatively. The occurrence of myocardial ischemia peaked in the early postoperative period (P < 0.05). On the contrary, in the clonidine group, 10 patients (33.3%) saw ischemic episodes preoperatively, 3 patients (10%) intraoperatively and 5 patients (16.7%) postoperatively. The incidence of myocardial ischemia in clonidine group was significantly lower than that in placebo group in intraoperative and postoperative periods. The mean arterial pressure was significantly lower in some clonidine-treated patients during perioperative periods (P < 0.05). A number of patients in clonidine group suffered from drowsiness (66.7%) after operation (P < 0.05), but they could be easily aroused. In regard to dryness of mouth, nausea and vomiting clonidine and control groups did not differ much (P > 0.05). Demerol consumption was significantly lower in clonidine group (43.7 +/- 4.6 mg) than in control group (76.3 +/- 3.7 mg, P < 0.05).

CONCLUSIONS

We conclude that premedication with oral clonidine can significantly reduce the incidence of perioperative myocardial ischemia in patients with CAD undergoing noncardiac surgeries. The incidence of myocardial ischemia in these patients is rather high during perioperative period, which deserves our exceptional caution.

Does postoperative pain induce emesis?

OBJECTIVE

The aim of this prospective, controlled study was to evaluate the risk factors for postoperative emesis in patients undergoing gynecologic surgery and receiving patient-controlled analgesia for three days.

METHODS

Six hundred twenty-five gynecologic patients with an American Society of Anesthesiologists physical status of I to III undergoing lower-abdominal surgeries were enrolled. A standard, general anesthetic technique was used. Postoperative pain was treated by a patient-controlled analgesia device with bolus intravenous doses of 1 mg morphine. For 3 days after surgery patients were assessed for occurrence of emesis, sedation, and pain intensity when at rest and during movement.

RESULTS

The incidence of emesis was 26% on postoperative day 1, 13% on day 2, and 4% on day 3. On all 3 days, patients' pain scores when at rest and when coughing were higher for those with emesis than for those without. During the first 2 postoperative days the patients with and those without emesis consumed similar amounts of morphine daily, but on the third day the patients with emesis consumed significantly more morphine than did those without emesis ( <0.05). Further logistic regression analysis showed that incident pain was the main risk factor for postoperative emesis on all 3 days.

CONCLUSIONS

The results suggested that postoperative pain was an associative risk factor to increase the incidence of emesis in these female patients.

Gender and pain upon movement are associated with the requirements for postoperative patient-controlled iv analgesia: a prospective survey of 2,298 Chinese patients

PURPOSE

To investigate prospectively the influence of patient characteristics upon, and the association of postoperative measurements with, the requirements for postoperative morphine and the assessment of resting pain and pain upon movement in Chinese patients.

METHODS

From January 1998 to December 1999, patients receiving patient-controlled iv morphine subsequent to general anesthesia and surgery at our institute (Kaohsiung Veterans General Hospital), were enrolled in the study. Demographic data (such as gender, age, weight, height and education level) and postoperative measurements, including pain scores at rest or during movement, sedation scores and morphine consumption, were recorded.

RESULTS

In total 2,298 patients were recruited. Females consumed significantly less morphine via patient-controlled analgesia (PCA) in the first three postoperative days than was the case for males (P <0.05). Gender was the strongest predictor for postoperative morphine requirements. Postoperative pain upon movement was another effective predictor for morphine requirement (P <0.05). Age, body height, body weight, education and operation sites were not associated with morphine consumption.

CONCLUSION

Gender and postoperative pain upon movement are the major factors influencing morphine requirement for patient-controlled iv morphine analgesia during the first three postoperative days in Chinese patients.

Innate diversity of adult human arterial smooth muscle cells: cloning of distinct subtypes from the internal thoracic artery

Vascular smooth muscle cells (SMCs) perform diverse functions and this functional heterogeneity could be based on differential recruitment of distinct SMC subsets. In humans, however, there is little support for such a paradigm, partly because isolation of pure human SMC subsets has proven difficult. We report the cloning of 12 SMC lines from a single fragment of human internal thoracic artery and the elucidation of 2 distinct cellular profiles. Epithelioid clones (n=9) were polygonal at confluence, 105+/-9 micrometer in length, and had a doubling time of 39+/-2 hours. Spindle-shaped clones (n=3) were larger (267+/-18 micrometer long, P<0.01) and grew slower (doubling time 65+/-4 hours, P<0.01). Both types of clones expressed smooth muscle (SM) alpha-actin, SM-myosin heavy chains, h-caldesmon, and calponin, but only spindle-shaped clones expressed metavinculin. Epithelioid clones displayed greater proliferation in response to platelet-derived growth factor-BB and fibroblast growth factor-2 and were more responsive to the migratory effect of platelet-derived growth factor-BB. Spindle-shaped clones showed more robust Ca(2+) transients in response to angiotensin II, histamine, and norepinephrine, crawled more quickly, and expressed more type I collagen. On serum withdrawal, spindle-shaped clones differentiated into a contraction-competent cell. A regional basis for diversity among SMCs was suggested by stepwise arterial digestion, which liberated small, SM alpha-actin-positive cells from the abluminal medial layers and larger SMCs from all layers. These results identify inherent SMC diversity in the media of the adult internal thoracic artery and suggest differential participation of SMC subsets in the regulation of human arterial behavior.

Vascular smooth muscle cells of recipient origin mediate intimal expansion after aortic allotransplantation in mice

Intimal expansion by vascular smooth muscle cells (SMCs) is a characteristic feature of graft vascular disease. Whether graft intimal SMCs arise from donor or recipient tissue is not well established but has important pathogenetic implications. We examined for the presence of male cells in the expanded intima of sex-mismatched mouse aortic allografts (C57BL/6-to-BALB/c) at 30 or 60 days after transplant by in situ hybridization using a Y-chromosome probe. Study groups included male-to-female allografts, female-to-male allografts, and female-to-female allografts in recipients previously engrafted with male bone marrow. Although intimal expansion developed in all allografts, male-to-female allografts lacked Y-chromosome-positive intimal cells. In contrast, such cells were abundant in female-to-male allografts and most of these cells co-labeled for smooth muscle alpha-actin by immunostain. Female-to-female allografts in recipients with male bone marrow showed a limited number of intimal Y-chromosome-positive cells. However, none of these clearly co-labeled for smooth muscle alpha-actin and their numbers declined throughout time, consistent with graft-infiltrating inflammatory cells. We conclude that intimal expansion of mouse aortic allografts is mediated by SMCs that originated from the recipient. There was little evidence of their derivation from the bone marrow, suggesting instead the adjacent host aorta as the primary source of intimal SMCs.

Enhanced detection of cardiac myocyte damage by polarized light microscopy. Use in a model of coxsackievirus B3-induced myocarditis

Although accurate detection of cardiac muscle damage is critical in the diagnosis of acute myocarditis or acute cellular rejection in both clinical and experimental settings, the histologic evaluation is frequently uncertain without specialized stains. In a study of adult male A/J mice infected with 2x10(5) plaque-forming units of myocarditic coxsackievirus B3, cardiac muscle injury causing myofibrillar disruption was detected as a loss of muscle birefringence by polarized light microscopy. The technique was corroborated by comparison with Masson's trichrome stain and was helpful for histologic examination especially at the early preinflammatory stages of lesion development or in fringe territories of focal lesions. Polarized light microscopy is thus an available means to enhance the histologic determination of cardiac myocyte damage and has specific advantage in an absence of specialized stains.

Cell surface-bound collagenase-1 and focal substrate degradation stimulate the rear release of motile vascular smooth muscle cells

To migrate in the vessel wall, smooth muscle cells (SMCs) must contend with abundant type I collagen. We investigated the mechanisms used by human SMCs to efficiently migrate on type I collagen, following stimulation with fibroblast growth factor-2 (FGF-2). FGF-2-stimulated migration was inhibited by a hydroxamic acid inhibitor of matrix metalloproteinases and by a neutralizing anti-collagenase-1 antibody. Moreover, migration speed of SMCs plated on mutant collagenase-resistant type I collagen was not increased by FGF-2. Time-lapse video analysis of unstimulated SMCs migrating on collagen revealed discrete phases of leading edge membrane extension and rear retraction, the latter often after rupture of an elongated tail. FGF-2 stimulation yielded a more synchronous, gliding motion with a collagenase-1-mediated decrease in tail ripping. Surface labeling of SMCs with biotin followed by immunoprecipitation revealed that a proportion of active collagenase-1, expressed in response to FGF-2, was bound to the plasma membrane. Pericellular collagen substrate cleavage was verified by immunostaining for neoepitopes generated by collagenase-1 action and was localized to discrete zones beneath the cell tail and the leading edge. These results identify a novel mechanism by which SMC migration on collagen is enhanced, whereby rear release from the substrate is orchestrated by the localized actions of membrane-bound collagenase-1.

Successful management of massive blood loss to extremely low hemoglobin in an elderly woman receiving spinal surgery

Blood transfusion is absolutely indicated in acute anemia when the hemoglobin concentration falls below 6 g/dL. Sometimes it challenges the anesthesiologists if the blood intended for urgent transfusion is not readily or quickly available. In this case report, we describe an 81-year-old lady who accidentally sustained acute anemia after spinal surgery with the hemoglobin concentration falling to 1.4 g/dL. During the long wait for the process of cross-matching tests and delivery of blood from the blood bank in the city remote from the hospital, we could do nothing but administer crystalloid and colloid solutions to maintain the circulatory volume to prevent low cardiac output. Epinephrine was given when systolic blood pressure fell below 70 mmHg. Central venous pressure and arterial blood pressure were monitored to guide all the treatment. Fortunately, patient fully recovered on postoperative day 3 without any adverse events.

The axis of interleukin 12 and gamma interferon regulates acute vascular xenogeneic rejection

Recent advances using transgenic animals or exogenous complement inhibitors have demonstrated prevention of hyperacute rejection of vascularized organs, but not graft loss due to acute vascular rejection. Using various wild-type and cytokine-deficient mice strains, we have examined the mechanisms of acute vascular rejection. C57BL/6 mice deficient in interleukin12 or gamma interferon showed faster acute vascular rejection than did wild-type mice. Furthermore, mice defective in B-cell development showed no acute vascular rejection. These results demonstrate that the axis of interleukin 12 and gamma interferon provides a survival advantage in vascularized xenografts by delaying or preventing acute vascular rejection caused by a B cell-dependent mechanism.

Effect of milrinone on postbypass pulmonary hypertension in children after tetralogy of Fallot repair

BACKGROUND

Postbypass pulmonary hypertension in surgical correction of tetralogy of Fallot (TOF) is a risk for right ventricular failure. Effective management remains a major challenge. Milrinone is a new drug with a unique mechanism of "inodilation", which offers both inotropic and vasodilatory effects. We attempted to determine if application of milrinone could improve cardiopulmonary dysfunction in children after TOF repair.

METHODS

We studied 10 children with postbypass pulmonary hypertension after TOF repair within six months. Heart rate, systolic pulmonary arterial pressure (PAP), systolic arterial blood pressure (SBP), pulmonary capillary wedge pressure and PAP/SBP ratio were recorded. Standard cardiopulmonary bypass (CPB) was performed. After CPB, if PAP/SBP was more than 0.5, pulmonary hypertension was suspected and milrinone was administered with a loading dose of 20 micrograms/kg followed by continuous infusion of 0.2 microgram/kg/minute. Hemodynamics were compared before and after administration of milrinone to evaluate its effect.

RESULTS

significant reduction in PAP/SBP ratio within 15 minutes was found after administration of milrinone. The effect persisted for 24 hours during continuous infusion of milrinone. No remarkable adverse effect was noted in the study.

CONCLUSIONS

We conclude that milrinone is effective in the management of pulmonary hypertension following CPB in children who underwent TOF repair.

Heat shock protein 47 is expressed in fibrous regions of human atheroma and Is regulated by growth factors and oxidized low-density lipoprotein

BACKGROUND

Heat shock protein 47 (Hsp47) is a stress protein that may act as a chaperone for procollagen. Its involvement in atherosclerosis is unknown.

METHODS AND RESULTS

Hsp47 expression in human coronary arteries was assessed by immunostaining. Strong focal expression was evident in atherosclerotic, but not normal, arteries and was prevalent in the collagenous regions. Double immunostaining revealed that all cells expressing type I procollagen also expressed Hsp47. Moreover, parallel regulation of proalpha1(I)collagen and Hsp47 mRNA expression occurred with cultured human smooth muscle cells stimulated with transforming growth factor-beta1 or fibroblast growth factor-2. However, a proportion of Hsp47-expressing cells in plaque did not express type I procollagen, and this pattern could be reproduced in culture. Heat shock and oxidized LDL stimulated the expression of Hsp47 mRNA by smooth muscle cells, without a concomitant rise in proalpha1(I)collagen expression.

CONCLUSIONS

These findings identify Hsp47 as a novel constituent of human coronary atheroma. Its localization to the fibrous cap, regulation by growth factors in parallel with type I procollagen, and selective upregulation by stress raise the possibility that Hsp47 is a determinant of plaque stability.

Effect of oral clonidine premedication on perioperative hemodynamic response and postoperative analgesic requirement for patients undergoing laparoscopic cholecystectomy

BACKGROUND

To investigate the clinical efficacy of oral clonidine premedication in anesthesia and analgesia in patients undergoing laparoscopic cholecystectomy (LC).

METHODS

One hundred and ten patients, scheduled for elective laparoscopic cholecystectomy, were recruited for the prospective, randomized, single-blind, comparative study. They were randomly allotted to either of the placebo or clonidine group. Patients of the placebo group (n = 65) were premedicated with oral antacid (alugel hydroxide 300 mg), while those in the clonidine group (n = 45) were premedicated with oral clonidine 150 micrograms prior to anesthesia. The premedication was given 60 to 90 min before the anticipated time of induction of anesthesia. Normocapnia was maintained throughout the perioperative period. Mass spectrometer was used to assess the inspired and expiratory concentrations of isoflurane, the anesthetic used for maintenance of anesthesia. Postoperative pain intensity, sedation scores, adverse events, time to the first dose of postoperative analgesic and cumulative analgesic requirement in 24 hours were recorded. Data were expressed as mean +/- SD.

RESULTS

Patients in the clonidine group displayed greater hemodynamic stability perioperatively and the isoflurane requirement was also reduced (30% less). The postoperative analgesic requirement was less (1.5 +/- 1.3 vs. 2.2 +/- 1.3 dose, P < 0.05) and the time for the first dose of analgesic was prolonged (411 +/- 565 vs. 264 +/- 441 min) in comparison with the placebo group but no statistic difference was found.

CONCLUSIONS

Oral clonidine premedication helped to provide perioperative hemodynamic stability, spared the use of isoflurane and reduced the requirement of postoperative analgesia so as to smoother the way to recovery in patients undergoing LC.

alpha5beta1 integrin expression and luminal edge fibronectin matrix assembly by smooth muscle cells after arterial injury

Fibronectin is secreted from the cell as a soluble protein that must then polymerize to regulate cell function. To elucidate the process of fibronectin matrix assembly in vascular disease, we immunostained sections of balloon-injured rat carotid artery for the fibronectin-binding alpha5beta1 integrin. Whereas alpha5beta1 integrin was not evident in the normal carotid artery, its expression was induced after a vascular injury. By 14 days, the alpha5beta1 integrin was localized exclusively to the less differentiated smooth muscle cells (SMCs) at the luminal surface of the neointima. Platelet-derived growth factor-BB, dominant in neointimal formation, selectively increased the expression of the alpha5beta1 integrin by human SMCs in culture. To track the assembly of fibronectin fibers, fluorescence-labeled soluble fibronectin protomers were added to cultured SMCs and to fresh segments of normal and balloon-injured rat carotid arteries. Fibronectin fiber formation in cultured SMCs could be detected within 10 minutes, and was blocked by an RGD peptide, an anti-beta1 integrin antibody, and an anti-alpha5beta1 integrin antibody, but not by an anti-beta3 integrin antibody. En face confocal microscopy of arterial segments revealed that soluble fibronectin had polymerized on the alpha5beta1 integrin-expressing SMCs of the luminal surface of the injured arterial neointima, but not on the alpha5beta1 integrin-negative neointimal SMCs below this or on the endothelial cells of uninjured arteries. Furthermore, in situ fibronectin assembly by the neointimal SMCs was inhibited by an RGD peptide and by an anti-beta1 integrin antibody. These studies indicate that a subpopulation of SMCs in the repairing artery wall orchestrates integrin-mediated fibronectin assembly.

The preoperative administration of intravenous dextromethorphan reduces postoperative morphine consumption

We evaluated the effect of dextromethorphan on postoperative pain management. Sixty ASA physical status I-III female patients undergoing major abdominal surgery underwent standardized general anesthesia. Thirty patients received an i.v. infusion of dextromethorphan 5 mg/kg before anesthetic induction (Pre group), whereas the remaining 30 patients received the same volume of isotonic sodium chloride solution, followed by a postoperative i.v. infusion of dextromethorphan 5 mg/kg (Post group). Patients in the Pre group received the same volume of isotonic sodium chloride solution postoperatively. All patients were then treated with patient-controlled i.v. analgesia, which administered a 0.6-mg bolus of morphine on demand (maximal 4 h dose 20 mg). The mean visual analog pain score during cough or movement and at rest were similar in the two groups in the first 3 days postoperatively. However, Post group patients consumed more morphine than Pre group patients during the first 2 days (P < 0.01). The sedation scores, patient satisfaction, and the incidence of morphine-related side effects were similar between the two groups. We conclude that the preoperative administration of dextromethorphan 5 mg/kg reduces postoperative morphine consumption compared with postoperative administration.

IMPLICATIONS

In this double-blinded study, we found that the preoperative administration of i.v. dextromethorphan 5 mg/kg, compared with postoperative administration, reduces postoperative morphine consumption, which may provide clinical evidence of preemptive or preventive analgesic effects of dextromethorphan.

Evidence from a novel human cell clone that adult vascular smooth muscle cells can convert reversibly between noncontractile and contractile phenotypes

Smooth muscle cells (SMCs) perform diverse functions that can be categorized as contractile and synthetic. A traditional model holds that these distinct functions are performed by the same cell, by virtue of its capacity for bidirectional modulation of phenotype. However, this model has been challenged, in part because there is no physiological evidence that an adult synthetic SMC can acquire the ability to contract. We sought evidence for this by cloning adult SMCs from human internal thoracic artery. One clone, HITB5, expressed smooth muscle alpha-actin, smooth myosin heavy chains, heavy caldesmon, and calponin and showed robust calcium transients in response to histamine and angiotensin II, which confirmed intact transmembrane signaling cascades. On serum withdrawal, these cells adopted an elongated and spindle-shaped morphology, random migration slowed, extracellular matrix protein production fell, and cell proliferation and [(3)H]thymidine incorporation fell to near 0. Cell viability was not compromised, however; in fact, apoptosis rate fell significantly. In this state, agonist-induced elevation of cytoplasmic calcium was even more pronounced and was accompanied by SMC contraction. Readdition of 10% serum completely returned HITB5 cells to a noncontractile, proliferative phenotype. Contractile protein expression increased after serum withdrawal, although modestly, which suggested that the switch to contractile function involved reorganization or sensitization of existing contractile structures. To our knowledge, the physiological properties of HITB5 SMCs provide the first direct demonstration that cultured human adult SMCs can convert between a synthetic, noncontracting state and a contracting state. HITB5 cells should be valuable for characterizing the basis of this critical transition.

Fatal pulmonary embolism in a child undergoing extra-ventricular drainage surgery--a case report

Thromboembolism is rather common in neurological patients and patients with brain tumor, who are bed-ridden or with partial immobile limb. In serious instances morbidity and mortality are inevitable. We present a case report on a fatal pulmonary embolism in a 2-year-old girl who underwent extra-ventricular drainage procedure under general anesthesia for occipital subdural effusion, a sequela of the former surgery undertaken to remove the choroid plexus papilloma 13 days ago. Sudden cardiac arrest occurred during induction of anesthesia and she finally succumbed in spite of vigorous cardiopulmonary resuscitation. Transthoracic and transesophageal echocardiography performed in the course of resuscitation disclosed thrombi of various sizes scattering in right atrium, the right ventricle, main pulmonary trunk, and the left pulmonary artery. The cause of death was thought to be severe obstruction of right ventricular outflow tract by large thrombi. The etiological factors which possibly led to the thrombosis were discussed, and the methods of diagnosis and treatment were also explored.

Pre-anesthetic oral clonidine is effective to prevent post-spinal shivering

BACKGROUND

Shivering is a common event during spinal anesthesia. Customarily we just treat it rather than prevent it. This study was designed to evaluate the efficacy of oral clonidine as a premedication to prevent post-spinal shivering.

METHODS

One hundred males of ASA physical status I-III, aged above 40, scheduled for elective urological surgery under spinal anesthesia, were included in this study. All participants were randomly divided into the clonidine and control groups. They received either oral clonidine 150 micrograms (n = 48) or placebo (n = 52) 90 min before spinal anesthesia in a double-blind fashion. Spinal blockade was induced with heavy bupivacaine to a dermatomal level near T10. The shivering was graded as: none, no perceptible tension of muscles observed; mild, slight muscle tonus (masseter muscle); moderate, real shivering (proximal muscles); and severe, generalized shivering (whole body). The tympanic membrane temperature was recorded 30 min after spinal anesthesia. Data were expressed as mean +/- standard deviation. Chi-square and Student's t-test were used. A p value less than 0.05 was considered statistically significant.

RESULTS

The incidence of post-spinal shivering, which was graded as none, mild, moderate, and severe, showed statistically significant differences (p < 0.05) between clonidine 150 micrograms and placebo (83% vs. 42%, 10% vs. 6%, 10% vs. 19%, 0% vs. 33%, respectively) during the 30 min immediately after spinal anesthesia. The respective mean tympanic temperature in oral clonidine and placebo groups showed no difference (clonidine vs. control = 35.9 +/- 0.8 degrees C vs. 35.9 +/- 0.7 degrees C).

CONCLUSIONS

Pre-anesthetic medication with oral clonidine 150 micrograms is effective to prevent post-spinal shivering in patients undergoing elective urological surgery.

Cardiovirulent coxsackieviruses and the decay-accelerating factor (CD55) receptor

Group B coxsackieviruses are etiologically linked with many human diseases including acute myocarditis and associated chronic dilated cardiomyopathy. Well-established CVB3 cardiovirulent strains (CVB3c(s)) with known phenotypic difference have been used to study the pathogenesis of virus-induced heart disease. The receptor-binding characteristics of cardiovirulent CVB3 are not known, but may represent one mechanism accounting for differences in disease virulence. In this study, interactions between CVB3c(s) and the decay-accelerating factor (DAF or CD55) cell surface receptor were examined. Anti-DAF monoclonal antibodies (MAbs) blocked virus binding and infection of susceptible HeLa cells. Virus binding was significantly reduced by treatment of these cells with phosphatidylinositol phospholipase C enzyme, which rendered them DAF-deficient CVB3c(s) exhibited a differential propensity for the DAF receptor, as several cardiovirulent strains interacted more strongly than others. However, virus binding and infection was always most effectively blocked by MAbs directed against the SCR 2 and 3 domains of DAF, suggesting that binding occurs at a similar site(s) on the molecule for all strains. Virus binding and internalization were associated with DAF down-regulation at the cell surface, as monitored by flow cytometry analysis. Cardiovirulent CVB3 did not interact with molecules functionally and/or structurally related to DAF, including CD35, CD46, Factor H, or C4-binding protein. Adenovirus type 2 (Ad2) does not use the DAF receptor. However, competitive binding assays between Ad2 and CVB1-6, CVB3c(s), anti-DAF MAbs, or DAF-reduced cells indicated that DAF is associated with Ad2 receptors on the HeLa cell membrane. In summary, this study indicates that DAF is an attachment receptor for cardiovirulent CVB3 and that DAF interaction may be important in the pathogenesis of CVB-mediated heart disease.

Fibroblast growth factor-2 potentiates vascular smooth muscle cell migration to platelet-derived growth factor: upregulation of alpha2beta1 integrin and disassembly of actin filaments

Fibroblast growth factor-2 (FGF-2) has been implicated in vascular smooth muscle cell (SMC) migration, a key process in vascular disease. We demonstrate here that FGF-2 promotes SMC motility by altering beta1 integrin-mediated interactions with the extracellular matrix (ECM). FGF-2 significantly increased surface expression of alpha2beta1, alpha3beta1, and alpha5beta1 integrins on human SMCs, as assessed by flow cytometry. The greatest increase was for the collagen-binding alpha2beta1 integrin. Despite this, FGF-2 did not increase SMC adhesion to type I collagen but instead promoted SMC elongation and SMC motility. The latter was evaluated by using a microchemotaxis chamber and by digital time-lapse video microscopy. Although FGF-2 was not chemotactic for human SMCs, cells preincubated with FGF-2 displayed a 3.1-fold increase in migration to the undersurface of porous type I collagen-coated membranes and a 2.1-fold increase in migration speed on collagen. Furthermore, chemotaxis to platelet-derived growth factor-BB on collagen was significantly greater in SMCs exposed to FGF-2. FGF-2-induced elongation and migration on collagen were inhibited by a blocking anti-alpha2beta1 antibody; however, SMC adhesion to collagen was unaffected. SMC migration on fibronectin was also enhanced by FGF-2, although less prominently: migration through porous membranes increased 1.8-fold, and migration speed increased 1.3-fold. Also, FGF-2 completely disassembled the smooth muscle alpha-actin-containing stress fiber network contemporaneously with the change in integrin expression and cell shape. We conclude that (1) exogenous FGF-2 promotes SMC migration and potentiates chemotaxis to PDGF-BB; (2) the promigratory effect of FGF-2 is especially prominent on type I collagen and is mediated by upregulation of alpha2beta1 integrin; and (3) FGF-2 disassembles actin stress fibers, which may promote differential utilization of alpha2beta1 integrin for motility but not adhesion. This dynamic SMC-ECM interplay may be an important mechanism by which FGF-2 facilitates SMC motility in vivo.

Coordinated effects of fibroblast growth factor-2 on expression of fibrillar collagens, matrix metalloproteinases, and tissue inhibitors of matrix metalloproteinases by human vascular smooth muscle cells. Evidence for repressed collagen production and activated degradative capacity

Fibroblast growth factor-2 (FGF-2) is an established mediator of smooth muscle cell (SMC) proliferation after vascular injury. However, the influence of FGF-2 on collagen fiber remodeling, which may be a prerequisite for vascular SMC accumulation, is not well understood. We determined that FGF-2 almost completely abrogated the formation of immunodetectable type I collagen fibers in the extracellular matrix of cultured human vascular SMCs. This was associated with reduced expression of pro alpha-chains for types I and III collagen, as assessed by Western blot analysis, and a corresponding reduction in collagen synthesis. Densitometry of Northern blots indicated a potent reduction of mRNA encoding pro alpha-chains for types I and III collagen and a minor reduction in mRNA for pro alpha-chains for type V collagen. Interstitial collagenase (MMP-1), which is required for degradation of collagen types I and III, was not expressed by SMCs under basal culture conditions, but expression was induced by FGF-2, with a potent, dose-dependent increase in MMP-1 protein in conditioned medium. Metalloproteinase inhibitors TIMP-1, TIMP-2, and TIMP-3 were expressed by unstimulated SMCs and were differentially regulated by FGF-2. TIMP-1 expression increased modestly, TIMP-2 expression was repressed, and TIMP-3 was relatively unaffected. The net effect on substrate degradation, as assessed by zymography of conditioned media, was induction of MMP-1 lytic activity by FGF-2, with no effect on the activity of MMP-2, MMP-3, or MMP-9. These data indicate that stimulation of human SMCs with FGF-2 establishes a phenotype in which collagen fiber production is repressed and the capacity for fiber degradation activated. This coordinated response may be critical for SMC accumulation during vascular remodeling as well as atherosclerotic plaque destabilization.

Intimal thickening develops without humoral immunity in a mouse aortic allograft model of chronic vascular rejection

BACKGROUND

The major threat to the long-term survival of cardiac allograft recipients is the development of diffuse intimal thickening in the allograft coronary arteries through mechanisms that are poorly understood. Although antidonor antibodies have been associated with the development of this condition, a causal relationship has not been established.

METHODS AND RESULTS

To determine whether humoral immune responses are necessary for the development of graft vascular disease, we performed abdominal aortic allografts from normal donor mice into different immunodeficient recipient mice: those lacking all donor-specific immune responses (severe combined immunodeficient [SCID] mice and recombination activating gene-1 [RAG-1]-deficient mice) and those lacking humoral immune responses alone owing to a targeted deletion of the joining region (JH) gene segments for the immunoglobulin heavy chain. At 6 to 9 weeks after transplantation, aortic allografts in normal immunocompetent recipients showed concentric intimal thickening extending the full length of the graft (percent luminal reduction, [%LR], 31.2 +/- 9.1 [mean +/- SD] and 38.5 +/- 3.6 in different donor-recipient strain combinations). In contrast, syngeneic (histocompatible) aortic grafts showed a normal-appearing vessel wall (%LR, 1.6 +/- 0.7). In both SCID and RAG-1-deficient recipients, aortic allografts showed a virtual absence of neointimal formation (%LR, 3.7 +/- 2.1 and 3.8 +/- 1.6 in SCID and RAG-1-deficient recipients, respectively), indicating a critical etiological role for alloimmune responses in this model. Importantly, allografts in JH-deficient mice showed marked intimal thickening (%LR, 35.7 +/- 7.9), with an appearance histologically indistinguishable from that of normal immunocompetent recipients.

CONCLUSIONS

Neointimal formation in graft vascular disease is critically dependent on alloimmune responses of the host. Humoral effector mechanisms, however, may not be required.

Evidence for rapid accumulation and persistently disordered architecture of fibrillar collagen in human coronary restenosis lesions

The pattern of collagen deposition after coronary angioplasty could significantly influence recurrent lesion formation. Traditional histologic assessments of coronary restenosis lesions have not identified abundant collagen fibers in restenotic tissue; however, these methods can suffer from lack of sensitivity and are not quantitative. We analyzed collagen architecture in 40 coronary lesions retrieved from patients by directional atherectomy, by exploiting the birefringent properties of fibrillar collagen. Picrosirius red-stained sections were illuminated with circularly polarized light, and fiber content and thickness were quantified by digital image analysis. Fifteen of 19 restenosis lesions (79%) and 1 of 21 native atherosclerosis lesions (5%) displayed a pattern of reactive intimal modeling, characterized by stellateshaped smooth muscle cells variably oriented in a loose extracellular matrix. There was an apparent paucity of collagen fibers in these regions based on staining with Movat's pentachrome, a traditional connective tissue stain. However, circular polarization light microscopy revealed an extensive distribution of collagen fibers in restenosis tissue, occupying 79.9% +/- 11.8% of the section area. Despite this high collagen content, the restenosis lesions were distinct from de novo atherosclerosis lesions in having a disordered collagen alignment, reduced fiber packing (p < 0.05), and thinner fibers (4.3 +/- 1.7 vs 9.2 +/- 4.3 microns, p < 0.001). Fiber diameter was greater in lesions retrieved between 3 and 17 months after angioplasty than in lesions retrieved between 1 week and 3 months (p < 0.05). However, fiber disorientation was evident in all lesions retrieved after 1 week, with little similarity to that of native plaque. Lesions retrieved within 1 week of angioplasty represented a distinct group with identical collagen features as in de novo atherosclerosis lesions, implying a different mechanism of restenosis in that population. We conclude that human coronary restenosis involves rapid accumulation of collagen fibers, which are persistently disordered. This may be critical in the development of restenosis and could significantly influence therapeutic attempts to control the process.

EMG spike trains of succinylcholine-induced fasciculations in myalgic patients

Single spike activity from the surface electromyogram (EMG) of fasciculations induced by succinylcholine (Sch) were studied from limb muscles (biceps, triceps, anterior tibialis and gastrocnemius) in 100 female patients. About 2/3 of them (n = 72) also received nondepolarizing neuromuscular pretreatment (atracurium or vecuronium). We observed from 20% of EMG records in the myalgic (but not in the nonmyalgic) patients, sustained spike trains (mean duration 1.47 s) that resembled motor units firing at physiologically high rates (mean 21.7 spikes/s). The finding reflects Sch's distal actions at the muscle spindle. The implications for myalgia and the possible involvement of micro damage at the extrafusal muscles are discussed.