Adenosine treatment delays postischemic hippocampal CA1 loss after cardiac arrest and resuscitation in rats

Resuscitation from cardiac arrest results in reperfusion injury that leads to increased postresuscitation mortality and delayed neuronal death. One of the many consequences of resuscitation from cardiac arrest is a derangement of energy metabolism and the loss of adenylates, impairing the tissue's ability to regain proper energy balance. In this study, we investigated the effects of adenosine (ADO) on the recovery of the brain from 12 min of ischemia using a rat model of cardiac arrest and resuscitation. Compared to the untreated group, treatment with adenosine (7.2 mg/kg) initiated immediately after resuscitation increased the proportion of rats surviving to 4 days and significantly delayed hippocampal CA1 neuronal loss. Brain blood flow was increased significantly in the adenosine-treated rats 1 h after cardiac arrest and resuscitation. Adenosine-treated rats exhibited less edema in cortex, brainstem and hippocampus during the first 48 h of recovery. Adenosine treatment significantly lowered brain temperature during recovery, and a part of the neuroprotective effects of adenosine treatment could be ascribed to adenosine-induced hypothermia. With this dose, adenosine may have a delayed transient effect on the restoration of the adenylate pool (AXP = ATP + ADP + AMP) 24 h after cardiac arrest and resuscitation. Our findings suggested that improved postischemic brain blood flow and ADO-induced hypothermia, rather than adenylate supplementation, may be the two major contributors to the neuroprotective effects of adenosine following cardiac arrest and resuscitation. Although adenosine did not prevent eventual CA1 neuronal loss in the long term, it did delay neuronal loss and promoted long-term survival. Thus, adenosine or specific agonists of adenosine receptors should be evaluated as adjuncts to broaden the window of opportunity in the treatment of the reperfusion injury following cardiac arrest and resuscitation.     

瞬目反射对微血管减压术后迟发性面神经麻痹的预测价值

目的 研究面肌痉挛微血管减压术(MVD)前后瞬目反射的变化,探讨术后迟发性面神经麻痹(DFP)的发生机制.方法 对印例面肌痉挛患者术前1d、术后第1、3、5天行瞬目反射检查,并观察DFP的发生.结果 56例术后未出现DFP,但瞬目反射检查仍表现为短暂的R1、R2潜伏期延长,且R1潜伏期于术后第5天,R2潜伏期于术后第3天恢复至术前水平.4例分别于术后第6-15天出现DFP症状,术后瞬目反射记录表现为R1潜伏期逐渐延长,甚至波形消失.结论 MVD对面神经功能存在影响,对于大部分患者(93%),面神经功能术后5 d内可自行恢复,而R1潜伏期逐渐延长甚至波形消失则表现为DFP.瞬目反射检查中R1波的监测对MVD术后DFP的发生有一定的预示作用.     

The effect of postoperative immobilization on short-segment fixation without bone grafting for unstable fractures of thoracolumbar spine

Background:

Controversy regarding the fixation level for the management of unstable thoracolumbar spine fractures exists. Often poor results are reported with short-segment fixation. The present study is undertaken to compare the effect of fixation level and variable duration of postoperative immobilization on the outcome of unstable thoracolumbar burst fractures treated by posterior stabilization without bone grafting.

Patients and Methods:

A randomized, prospective, and consecutive series was conducted at a tertiary level medical center. Thirty-six neurologically intact (Frankel type E) thoracolumbar burst fracture patients admitted at our institute between February 2003 and December 2005 were randomly divided into three groups. Group I (n = 15) and II (n = 11) patients were treated by short-segment fixation, while Group III (n = 10) patients were treated by long-segment fixation. In Group I ambulation was delayed to 10th-14th postoperative day, while group II and III patients were mobilized on third postoperative day. Anterior body height loss (ABHL) percentage and increase in kyphosis as measured by Cobb''s angle were calculated preoperatively, postoperatively, and at follow-up. Denis Pain Scale and Work Scales were obtained during follow-up.

Results:

Mean follow-up was 13.7 months (range 3-27 months). At the final follow-up the mean ABHL was 4.73% in group I compared with 16.2% in group II and 6.20% in group III. The mean Cobb''s angle loss was 1.8° in group I compared with 5.91° in group II and 2.3° in group III. The ABHL difference between groups I and II was significant (P = 0.0002), while between groups I and III was not significant (P = 0.49).

Conclusion:

The short-segment fixation with amenable delayed ambulation is a valid option for the management of thoracolumbar burst fractures, as radiological results are comparable to that of long-segment fixation with the advantage of preserving maximum number of motion segments.     

Time Course of Symptom Disappearance after Microvascular Decompression for Hemifacial Spasm

Objective

This study is to investigate time course of symptom disappearance in patients whose spasm relieved completely after microvascular decompression (MVD).

Methods

Of 115 patients with hemifacial spasm (HFS) who underwent MVD from April 2003 to December 2006, 89 patients who had no facial paralysis after operation and showed no spasm at last follow-up more than 1.5 years after operation were selected. Symptom disappearance with time after MVD was classified into type 1 (symptom disappearance right after operation), type 2 (delayed symptom disappearance) and type 3 (unusual symptom disappearance). Type 2 was classified into type 2a (with postoperative silent period) and type 2b (without silent period).

Results

Type 1, type 2a, type 2b and type 3 were 38.2%, 48.37%, 12.4% and 1.1%, respectively. Delayed disappearance group (type 2) was 60.7%. Post-operative symptom duration in all cases ranged from 0 to 900 days, average was 74.6 days and median was 14 days. In case of type 2, average post-operative symptom duration was 115.1 days and median was 42 days. Five and 3 patients required more than 1 year and 2 years, respectively, until complete disappearance of spasm. In type 2a, postoperative silent period ranged from 1 to 10 days, with an average of 2.4 days.

Conclusion

Surgeons should be aware that delayed symptom disappearance after MVD for HFS is more common than it has been reported, silent period can be as long as 10 days and time course of symptom disappearance is various as well as unpredictable.     

Delayed pharmacological pre-conditioning effect of mitochondrial ATP-sensitive potassium channel opener on neurologic injury in a rabbit model of spinal cord ischemia

Background: Diazoxide, pharmacological openers of mitochondrial ATP-sensitive potassium channels have been shown to induce early pre-conditioning in the spinal cord. Here, the authors investigated whether diazoxide also induce delayed pre-conditioning and thereby reduce neurologic complications using a rabbit model of spinal cord ischemia.
Methods: Infrarenal blood flow was interrupted for 20 min in 21 rabbits. Non-treated control animals received no pre-treatment. Diazoxide (5 mg/kg) were given 48 h before 20 min ischemia in the 48-h DZ group, whereas 15-min DZ group received diazoxide (5 mg/kg) 15 min before 20-min ischemia. Neurological functions were evaluated using Johnson scores for 3 days after reperfusion, after which, spinal cords were procured for hematoxylin and eosin staining for cell counting.
Results: Johnson scores revealed a marked improvement in both the diazoxide-treated groups vs. the non-treated control group at 3, 24, 48, and 72 h after reperfusion ( P <0.01). The histologic changes were proportional to the Johnson scores, with better preservation of motor neuron numbers in the animals of the 48-h DZ and 15-min DZ group relative to the non-treated controls (81±12, 90±10, 50±23 motor neurons, respectively, P <0.01). No difference was found between the 48-h DZ group and 15-min DZ group with respect to the Johnson scores or neuron numbers.
Conclusions: The study demonstrates that pre-treatment with diazoxide 48 h before ischemia, induce delayed pharmacological pre-conditioning, thereby significantly improving clinical neurologic scores and histologic findings in this animal model.     

Initial pretherapeutic assessment of anal epidermoid carcinoma

Anal epidermoid carcinoma is a rare malignant tumor, comprising less than 5% of all carcinomas of the colon, rectum, and anus. The primary therapy now includes radiotherapy, often in combination with chemotherapy. Radical surgery is now rarely indicated. Therapeutic indications are based on locoregional staging, the presence of visceral metastases and an evaluation of the medical history. Anorectal endosonography is helpful in evaluating locoregional extension. In addition, magnetic resonance imaging, positron emission tomography scanning and inguinal sentinel lymph node procedure should play a role in a more selective approach in patients with anal carcinoma.     

Dim light melatonin onset (DLMO): a tool for the analysis of circadian phase in human sleep and chronobiological disorders

The circadian rhythm of melatonin in saliva or plasma, or of the melatonin metabolite 6-sulphatoxymelatonin (aMT6S) in urine, is a defining feature of suprachiasmatic nucleus (SCN) function, the endogenous oscillatory pacemaker. A substantial number of studies have shown that, within this rhythmic profile, the onset of melatonin secretion under dim light conditions (the dim light melatonin onset or DLMO) is the single most accurate marker for assessing the circadian pacemaker. Additionally, melatonin onset has been used clinically to evaluate problems related to the onset or offset of sleep. DLMO is useful for determining whether an individual is entrained (synchronized) to a 24-h light/dark (LD) cycle or is in a free-running state. DLMO is also useful for assessing phase delays or advances of rhythms in entrained individuals. Additionally, it has become an important tool for psychiatric diagnosis, its use being recommended for phase typing in patients suffering from sleep and mood disorders. More recently, DLMO has also been used to assess the chronobiological features of seasonal affective disorder (SAD). DLMO marker is also useful for identifying optimal application times for therapies such as bright light or exogenous melatonin treatment.     

磷酸三邻甲苯酯对母鸡神经组织线粒体膜通透性的影响

目的 研究磷酸三邻甲苯酯(tri-ortho-cresyl phosphate,TOCP)对母鸡神经组织线粒体膜通透性的影响,探讨有机磷诱导迟发性神经毒性的机制.方法 成年罗曼母鸡随机分为4组,每组24只,TOCP溶解于玉米油中,染毒组分别按185、375、750 mg/kg经灌胃一次性染毒,灌胃量为0.65 ml/kg,对照组给予等体积玉米油.分别于染毒后第1、5、15、21天处死动物,迅速剥离母鸡大脑、小脑、脊髓组织,分离其线粒体,测定线粒体膜通透性和跨膜电位的改变.结果 染毒组与对照组相比,大脑中线粒体膜通透性改变不明显;小脑375、750 mg/kg组在染毒第1、5天时通透性有明显增加(P＜0.05);染毒第1天时3个染毒组脊髓中线粒体膜通透性均明显增加(P＜0.05),染毒第5、15天时375、750mg/kg组膜通透性明显增加(P＜0.05).各剂量组间及各时间点之间跨膜电位均未观察到明显改变.结论 TOCP能明显增加母鸡小脑及脊髓中线粒体膜通透性.     

Gamma-band activity dissociates between matching and nonmatching stimulus pairs in an auditory delayed matching-to-sample task

Electro- and magnetoencephalography studies have suggested that increased gamma-band activity (GBA) is a correlate of activated neural stimulus representations. In this study, a delayed matching-to-sample paradigm for auditory spatial information was employed to investigate the role of magnetoencephalographic gamma-band activity in the differentiation between matching and nonmatching stimulus pairs. Twelve subjects made same-different judgments about the lateralization angle of pairs of filtered noise stimuli (S1 and S2) presented with 0.8-s delays. One half of the subjects had to respond to matching stimulus pairs, the other half to nonmatching stimulus pairs. Cortical oscillatory activity in the memory task was compared to a control task requiring the detection of background noise intensity changes. Memory-related GBA increases were revealed over midline parietal areas in the middle of the delay phase and during the presentation of S2 and over frontocentral areas at the end of the delay phase. This replicated previous findings. In addition, nonmatching trials were associated with increased GBA over right parietal areas in response to S2. The midline parietal GBA increase during S2 in the memory condition may have reflected the representation of S1 needed for a comparison between S1 and S2. When S1 and S2 were identical, no further representation was required. In contrast, for nonmatching pairs, a second representation was activated over right parietal areas.