Haemodynamic effects of atropine during halothane or isoflurane anaesthesia in infants and small children

In this study, two-dimensional and pulsed Doppler echocardiography were used to measure cardiovascular changes before and after IV atropine in 31 infants and small children during halothane (n = 15) or isoflurane (n = 16) anaesthesia. Prior to induction of anaesthesia heart rate (HR), mean blood pressure (MBP), and two0dimensional echocardiographic dimensions of the left ventricle and pulmonary artery bloodflow velocity were measured by pulsed Doppler echocardiography. Cardiovascular measurements were repeated while anaesthesia was maintained at 1.5 MAC halothane (n = 15) or isoflurane (n = 16). Atropine 0.02 mg·kg⁻¹ IV was then administered and two minutes later, a third set of cardiovascular data was obtained. Heart rate decreased during halothane anaesthesia but did not change significantly during isoflurane anaesthesia. Mean blood pressure, cardiac output (CO) and stroke volume (SV) decreased similarly during 1.5 MAC halothane or isoflurane anaesthesia. Ejection fraction (EF) decreased and left ventricular end-diastolic volume (LVEDV) increased significantly in bothgroups, but decreases in EF (32 ± 5 percentvs18 ± 5 per cent) and increases in LVEDV (18 ± 7 per cent vs7 ± 5 per cent) were significantly greater during halothane than during isoflurane anaesthesia. Following atropine, HR increased more in the patients maintained with halothane (31 ± 6 per cent), than during isoflurane anaesthesia (18 ± 5 per cent). Atropine increased CO in both groups of patients, but SV and EF remained unchanged. When compared with awake values, HR increased similarly and significantly (18 ± 4 per cent) following atropine in both groups, and CO returned to control levels. Halothane decreased EF and increased LVEDV more than isoflurane at 1.5 MAC end— expired anaesthetic levels. Atropine did not diminish the myocardial depression produced by halothane or isoflurane. The increase in CO following atropine during halothane and isoflurane anaesthesia in infants and small children is the result of increases in HR alone. Nous avons utilisé un appareil à échocardiographie bi-dimensionnelle couplé à un Doppler pulsé chez des bébés et de jeunes enfants pour évaluer l’impact hémodynamique de l’halothane (n = 15) et de l’isoflurane (n = 16) et la modification possible de ces effets par l’atropine. Nous avons mesure la frequence cardiaque (FC), la pression artérielle moyenne (PAM), la dimension de la cavité ventriculaire gauche (par écho bi-dimensionnelle) et la vélocité du flot sanguin pulmonaire (par Doppler) et ce, en trois occasions soit avant l’induction, après l’instauration de 1.5 MAC d’halothane ou d’isoflurane et finalement, deux minutes après l’injection IV de 0.02 mg·kg⁻¹ d’atropine. On ne nota une baisse de la frequence cardiaque qu’avec l’halothane tandis que la PAM, le débit cardiaque (DC) et le volume d’éjection (VE) diminuaient autant avec l’un ou l’autre anesthésique. La diminution de la fraction d’éjection (FE) et l’augmentation du volume télédiastolique du ventricule gauche (VTDVG) significatives pour les deux groupes, étaienl plus marqué avec l’halothane qu’avec l’isoflurane: FE 32 ± 5 pour cent vs18 ±5 pour cent; VTDVG 18 ± 7 pour cent vs 7 ± 5 pour cent. Avec l’atropine, la FC monta plus dans le groupe halothane (31 ± 6 pour cent) que dans le groupe isoflurane (18 ± 5 pour cent), le DC augmentant dans les deux groupes, alors que le VE et la FE demeuraient inchangés. Comparée aux mesures pré-induction, l’atropine amenait une hausse significative de la FC, semblable dans les deux groupes (18 ± 4 pour cent) et restaurait le DC. Donc, chez les bebes et les jeunes enfants, a 1.5 MAC, l’halothane diminue la FE et augmente le VTDVG plus que ne le fait l’isoflurane. L’atropine ne modifie pas la depression myocardique et elle ne restaure le DC que par une hausse de la FC.

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Supported by PHS Grant No. 8507300 from the College of Medicine, University of Iowa Hospital, Iowa City, IA.     

陡脉冲电场对荷瘤BALB/c小鼠癌细胞杀伤效应的实验研究

观测陡脉冲电场对荷瘤BALB/c小鼠癌细胞的杀伤效应。处理后的癌细胞在光镜下表现为细胞核固缩、核碎裂、核溶解;在电镜下表现为异染色质增加,边集,呈团块样改变,细胞质肿胀,脂滴数量增加,质膜破裂;核固缩,碎裂,线粒体肿胀。实验揭示了陡脉冲电场能有效地杀伤癌细胞,明显抑制了荷瘤小鼠恶性肿瘤的生长、增殖,有着良好的应用前景。     

Engineered human dicentric chromosomes show centromere plasticity

The centromere is essential for the faithful distribution of a cell's genetic material to subsequent generations. Despite intense scrutiny, the precise genetic and epigenetic basis for centromere function is still unknown. Here, we have used engineered dicentric human chromosomes to investigate mammalian centromere structure and function. We describe three classes of dicentric chromosomes isolated in different cell lines: functionally monocentric chromosomes, in which one of the two genetically identical centromeres is consistently inactivated; functionally dicentric chromosomes, in which both centromeres are consistently active; and dicentric chromosomes heterogeneous with respect to centromere activity. A study of serial single cell clones from heterogeneous cell lines revealed that while centromere activity is usually clonal, the centromere state (i.e. functionally monocentric or dicentric) in some lines can switch within a growing population of cells. Because pulsed field gel analysis indicated that the DNA at the centromeres of these chromosomes did not change detectably, this switching of the centromere state is most likely due to epigenetic changes. Inactivation of one of the two active centromeres in a functionally dicentric chromosome was observed in a percentage of cells after treatment with Trichostatin A, an inhibitor of histone deacetylation. This study provides evidence that the activity of human centromeres, while largely stable, can be subject to dynamic change, most likely due to epigenetic modification.     

Effect of pulsed hydrodynamic influences on blood cells in vitro and in vivo

(Presented by Academician of the Academy of Medical Sciences of the USSR A. N. Klimov.) Translated from Byulleten' Éksperimental'noi i Biologii i Meditsiny, Vol. 110, No. 12, pp. 604–606, December, 1990.     

极低频脉冲电磁场对新生大鼠成骨细胞的影响

目的：观察极低频脉冲电磁场（pulsed electromagnetic fields，PEMF）对体外培养成骨细胞增殖、分化、体外矿化的影响。方法：采用频率为15Hz、强度为5mT、占空比为15％的PEMF作用于成骨细胞，检测成骨细胞的增殖、碱性磷酸酶（alkaline phosphatase，ALP）活性以及体外矿化指标。结果与结论：PEMF显著促进成骨细胞增殖和体外矿化，抑制ALP活性作用。     

人工假肢膝关节微电脑控制装置的研究

高位截肢的伤残病人，即使安装了人工假肢，也因为人工假肢的关节不能自由活动，因而行走起来很吃力，动作不协调，姿态不美观。如果在人工假肢的关节处安装一个步进电机，采用微电脑控制技术，使步进电机按照人的意志转动，那么人在行走（或奔跑、弹跳、上下楼梯、下蹬起立等）时，假肢的逼真程度将会大大提高，动作也就十分自然。本文就这种构想谈了制作过程。     

1 MHz腔内射频加热辐射器在体模和犬颈段食管中的热场分布

目的 在肌肉等效体模及Beagle犬颈段食管中测定ZRL—Ⅱ型食管腔内加热辐射器的温度分布，探讨其热场分布能否满足食管癌加热治疗的临床需要。方法 ①在肌肉等效体模中测定ZRL—Ⅱ型食管腔内射频加热辐射器的温度分布，②Beagle犬用氯胺酮麻醉、固定。将腔内加热辐射器插入食管腔内，加热45min后分层解剖犬的颈部，同时测量食管外壁、气管、食管周围软组织中的温度。结果 ①在肌肉等效体模中距离导管囊表面1cm的环形体内的温度在43．2℃～43．6℃之间；在距离导管囊表面2cm的环形体内的温度在42．6℃～43．3℃之间，在距离导管囊表面3cm的环形体内的温度在42．6℃～42．8℃之间。②测得Beagle犬颈段食管腔内和外壁的温度为43．5℃，气管内为38．0℃，主动脉旁38．0℃，距食管外壁1cm处的软组织温度为40-3℃，距食管外壁2cm处的软组织温度为39．0℃，而颈部皮下的温度是37．5℃。结论 ①ZRL-Ⅱ型射频食管腔内加热辐射器的热场分布满足临床食管腔内加热的需要，②体模测定与活体动物测定，热场分布存在一定差异，需进一步研究。     

Can low intensity pulsed ultrasound (LIPUS) be used as an alternative to revision surgery for patients with non-unions following fracture fixation?

BackgroundNon-union is a significant complication of fracture fixation surgery, and can negatively impact a patient’s quality of life. Low intensity pulsed ultrasound (LIPUS) has been used to treat delayed or non-unions previously in the literature. The aim of this study was to determine the success rate of LIPUS treatment in patients with chronic fracture non-unions, and to establish the effect of systemic or local factors on its success.MethodsThis was a retrospective, observational study which included all patients undergoing LIPUS treatment in a single institution. Patients deemed suitable for LIPUS underwent treatment for a period of 6 months from initiation. They were followed up with sequential radiographs to assess union at intervals of 6 weeks, 3 months, 6 months and 1 year. LIPUS treatment was considered to be successful when patients achieved clinical and radiological union, without the need for revision surgery.ResultsA total of 46 patients were included in the study; 8 were lost to follow – up, leaving 38 patients for the final analysis. The mean age of patients was 47.03 ± 19.7 with a male to female ratio of 1.2:1. Union was achieved in 57.89%; the rest underwent revision surgery. There was no significant association between outcomes after LIPUS treatment and patients’ age, gender, smoking status or type of non-union. Patients with a small inter-fragment bone gap were more likely to have a successful outcome after LIPUS (p = 0.041). Time to treatment did not have a statistically significant impact on outcomes after LIPUS. Interestingly, all 6 patients with diabetes in the study managed to achieve union after LIPUS.ConclusionsThis study demonstrates that LIPUS is not successful in a large proportion of patients with established fracture non-unions. However, it does represent a low risk treatment modality as an alternative to revision surgery, especially for patients with diabetes who have a small inter – fragment bone gap. More research in the form of large randomised controlled trials needs to be carried out to further assess the role of LIPUS in the treatment of non-unions.