Thyroid hormone effects on the proton permeability of rat liver mitochondria

The effect of thyroid status on passive permeability of liver mitochondrial inner membrane was studied in euthyroid (EU), hyperthyroid (HYPER), hypothyroid (HYPO) rats and hypothyroid rats treated with a single dose of 3,3',5-triiodothyronine (HYPO + T3). Respiration was titrated with uncoupler and plotted against uncoupler concentration to calculate proton permeability. The passive permeability was the same in EU, HYPER, and HYPO + T3 rats, but was significantly lower in HYPO mitochondria. The State IV respiration rates were the same as the oligomycin-inhibited rats for EU, HYPO and HYPO + T3 rats, but in HYPER rats the oligomycin rate was less than the State IV rate. The data show that hypothyroid mitochondria have decreased permeability of the inner membrane which can be normalized by a single dose of T3. Hyperthyroid mitochondria show increased oligomycin-sensitive ATPase activity in State IV, a possible mechanism of the enhanced respiratory rate.     

Convergence of neural systems processing stimulus associations and coordinating motor responses

A sensory-sensory learning paradigm was used to measure neural changes in humans during acquisition of an association between an auditory and visual stimulus. Three multivariate partial least-squares (PLS) analyses of positron emission tomography data identified distributed neural systems related to (i) processing the significance of the auditory stimulus, (ii) mediating the acquisition of the behavioral response, and (iii) the spatial overlap between these two systems. The system that processed the significance of the tone engaged primarily right hemisphere regions and included dorsolateral prefrontal cortex, putamen, and inferior parietal and temporal cortices. Activity changes in left occipital cortex were also identified, most likely reflecting the learned expectancy of the upcoming visual event. The system related to behavior was similar to that which coded the significance of the tone, including dorsal occipital cortex. The PLS analysis of the concordance between these two systems showed substantial regional overlap, and included occipital, dorsolateral prefrontal, and limbic cortices. However, activity in dorsomedial prefrontal cortex was strictly related to processing the auditory stimulus and not to behavior. Taken together, the PLS analyses identified a system that contained a sensory-motor component (comprised of occipital, temporal association and sensorimotor cortices) and a medial prefrontallimbic component, that as a group simultaneously embodied the learning-related response to the stimuli and the subsequent change in behavior.      

A novel strategy to limit blood donor exposure and blood waste in multiply transfused premature infants

Small, premature infants require frequent small-volume transfusions. Traditional methods of transfusion expose these infants to multiple blood donors. It has recently been demonstrated that multiple donor exposures can be safely prevented in these infants by the assignment of fresh units to them and by the use of a sterile connecting device to remove blood for transfusion, as needed until the expiration of the unit. However, the program resulted in the wasting of approximately 60 percent of the blood in each unit. STUDY DESIGN AND METHODS: To minimize blood waste without compromising the goal of limiting donor exposure, a model designed to predict each infant's transfusion requirements was investigated. The model assigned infants predicted to have high transfusion requirements to receive blood from a unit dedicated to their individual use. All other infants were assigned to receive blood from a unit that could be shared among as many as four similar infants. Infant donor exposure and blood unit wastage after institution of the infant assignment model were compared with the same measurements obtained before the use of the model, during which time infants were assigned to dedicated units at the discretion of the physician. RESULTS: The numbers of transfusions per infant (3.5 +/− 2.3) and of donor exposures per infant (1.5 +/− 0.7) under the assignment model were unaltered from those in controls (4.1 +/− 2.9 transfusions and 1.6 +/− 0.8 donor exposures); however, there was significantly less blood wastage in the group assigned to shared units (32 +/− 28%) than in the group assigned to dedicated units (62 +/− 17%; p < 0.05) or than was seen in an earlier study (60 +/− 23% wasted; p < 0.05). CONCLUSION: Improved management of blood resources can be achieved within the context of a transfusion program designed to safely limit donor exposure in infants who require frequent transfusion.     

急性缺血再灌注肾损伤过程中Mg2+及K+协同胰岛素的对抗效应

目的:在肾移植术后可能发生急性缺血再灌注性肾损伤.作者前期实验表明在肾缺血再灌注期间注射胰岛素可减轻缺血再灌注肾损伤,在此基础上,在胰岛素溶液中加入天冬氨酸钾镁,观察Mg2 ,K 协同胰岛素对家兔急性肾缺血再灌注损伤的影响,并分析其可能机制.方法:实验于2002-02/04在泸州医学院生理实验室完成,动物实验方法符合动物伦理学要求.①实验材料及方法:选用健康成年日本大耳白兔27只,按随机数字表法分为3组(n=9),即缺血再灌注组、缺血再灌注胰岛素处理组及对照组,前两组采用钳夹肾动脉法建立急性肾缺血再灌注肾损伤模型,缺血再灌注胰岛素处理组再灌注的同时给予胰岛素溶液,含胰岛素3 U/kg,葡萄糖1.5 g/kg,K 4 mg/kg,Mg2 1.7 mg/kg.②实验评估:分别观察3组动物缺血再灌注2 h,48 h后,血清尿素氮、血糖、血清及肾组织中丙二醛含量以及肾组织超微结构变化.结果:23只动物进入结果分析.①肾缺血再灌注48 h后,缺血再灌注组血清尿素氮含量显著高于对照组(P＜0.01),缺血再灌注胰岛素处理组与对照组差异无显著性意义(P＞0.05).②缺血再灌注组血清及肾组织中丙二醛含量显著高于对照组(P＜0.05),缺血再灌注胰岛素处理组丙二醛含量显著低于缺血再灌注组(P＜0.05).③缺血再灌注2 h后,3组动物血糖均较术前增高,但以缺血再灌注组增高更为显著,与对照组比较差异具有显著性意义(P＜0.05),缺血再灌注胰岛素处理组与对照组差异无显著性意义(P＞0.05).④对照组肾组织超微结构正常,缺血再灌注组肾组织呈变性和坏死改变,缺血再灌注胰岛素处理组肾组织轻度变性.结论:Mg2 ,K 可协同胰岛素减轻家兔急性缺血再灌注性肾损伤,其作用途径可能和降低血糖、抗自由基损伤、改善能量代谢、减轻钙超载、防止低血钾等因素有关.     

Training in endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) represents an important advancement in the therapy of early neoplastic gastrointestinal lesions by providing higher en-bloc curative resection rate with lower recurrence compared to endoscopic mucosal resection (EMR) and by sparing the involved organ and protecting patient’ s quality of life. Despite these advantages ESD is associated with long procedure times and a higher rate of complications, making ESD a challenging procedure which requires advanced endoscopic skills. Thus, there has been a recognized need for structured training system for ESD to enhance trainee experience and, to reduce the risks of complications and inadequate treatment. ESD has a very flat learning curve. However, we do not have uniformly accepted benchmarks for competency. Nevertheless, it appears that, in Japan, more than 30 supervised gastric ESD procedures are required to achieve technical proficiency and minimize complications. A number of training algorithms have been pro-posed in Japan with the aim to standardize ESD training. These algorithms cannot be directly applied in the West due to substantial differences including the availability of highly qualified mentors, the type of pathology seen, choice of devices, and trainee’s background. We propose a training algorithm for Western physicians which integrates both hands-on training courses, animal model work as well as visits to expert centers. No specific preceptor training programs have been yet developed but there is a consensus that these programs are important for permeation of ESD worldwide.     

Rotator cuff tear arthropathy

Rotator cuff tear arthropathy represents a spectrum of shoulder pathology characterized by rotator cuff insufficiency, diminished acromiohumeral distance with impingement syndromes, and arthritic changes of the glenohumeral joint. Additional features may include subdeltoid effusion, humeral head erosion, and acetabularization of the acromion. Although the progression of rotator cuff tears seems to play a role in the development of cuff tear arthropathy, information is lacking regarding the natural progression of rotator cuff tears to cuff tear arthropathy. Controversy remains about the role of basic calcium phosphate crystals in the development of cuff tear arthropathy. Nonsurgical management is the first line of treatment in most patients. Traditionally, surgical management of rotator cuff tear arthropathy has been disappointing because of the development of complications long-term and poor patient satisfaction with functional outcomes. Recent studies, however, report promising experience with reverse ball-and-socket arthroplasty.     

Hyperfunctioning and nonhyperfunctioning benign adrenal cortical lesions: characterization and comparison with MR imaging

The authors evaluated the potential of magnetic resonance (MR) imaging at 0.35 T to permit differentiation of nine hyperfunctioning adrenal cortical lesions from 21 nonhyperfunctioning adrenal cortical adenomas. Both qualitative data (visual assessment) and quantitative data (signal intensity ratios, T1, and T2) were used for tissue characterization. With a 2,000/56-100 sequence (repetition time msec/echo time msec), the majority of lesions were visually isointense to liver. Of 34 quantitative measures, only lesion-liver and lesion-kidney intensity ratios at 2,000/150 showed statistically significant differences among nonhyperfunctioning adenomas, aldosterone-producing lesions, and corticosteroid-producing lesions; however, the authors question the significance of these differences because of the abundant noise associated with the 2,000/150 sequence. The results suggest that nonhyperfunctioning adrenal cortical adenomas cannot be distinguished from benign hyperfunctioning cortical lesions with use of MR imaging at 0.35 T.     

Early osteonecrosis of the femoral head: detection in high-risk patients with MR imaging

To determine whether magnetic resonance (MR) imaging can demonstrate the early stages of osteonecrosis that are not detectable radiographically, the authors compared radiologic findings with histologic results in seven patients at high risk for osteonecrosis of the femoral head. Radiography and MR imaging were performed, and proximal femoral intramedullary pressures were measured in all patients, even if results from imaging studies were normal. If the pressures were elevated, core decompression with biopsy was performed. Seven patients had elevated pressures in 11 hips. Of 11 hips from which biopsy specimens were taken, all had histologic evidence of osteonecrosis. However, in only five were the MR imaging findings consistent with osteonecrosis. In the remaining six hips with osteonecrosis, MR imaging findings were normal. Sensitivity of MR imaging in detection of osteonecrosis was 46%. The authors conclude that normal MR imaging results in high-risk patients do not rule out the presence of osteonecrosis.