Attenuated sympathetic tone augments nitrous oxide-induced myocardial depression during high-dose fentanyl anaesthesia in dogs

The purpose of this study was to determine whether centrally mediated sympathetic tone exerts compensatory effects on nitrous oxide-induced myocardial depression during high-dose fentanyl anaesthesia. The cardiovascular responses to 60 minutes of nitrous oxide administration after fentanyl, 100 micrograms.kg-1, were examined in 18 dogs with or without autonomic blockade induced by hexamethonium. Decreases of cardiac output and left ventricular stroke work were significantly greater in dogs with autonomic blockade (n = 9) by about 20 per cent of baseline values than in dogs without autonomic blockade (n = 9) at 30, 45, and 60 min. Similarly, left ventricular dP/dt was reduced more in dogs with autonomic blockade than in dogs without autonomic blockade, but this difference was only significant at the 60-min period. It is concluded that the sympathetic nervous system provides partial compensation for myocardial depression induced by nitrous oxide in the presence of high-dose fentanyl, suggesting that large doses of fentanyl do not ablate the centrally mediated sympathomimetic effects of nitrous oxide.     

Thoracoscopic surgery for lung cancer.

Thoracoscopic surgery has raised awareness in minimizing invasiveness in respiratory surgery. In the case of lung cancer, technical difficulties associated with standard curative surgery may not allow the use of a total thoracoscopic procedure. Although thoracoscopic lung cancer surgery is minimally invasive and safe, it demands a high level of skill and care. Surgery is often performed using a small incision and direct vision, with the thoracoscope serving as a light source. However, thoracoscopic surgery is expected to progress further in the near future. In addition, a new surgical system that comprehends both open and video-assisted thoracic surgery (VATS) may gain popularity.     

Serum Levels of Free Insulin-Like Growth Factor (IGF)-I in Normal Children

Serum levels of free insulin-like growth factor (IGF)-I were measured by immunoradiometric assay (IRMA) in fasting sera of 137 normal boys and 120 normal girls aged from 8 to 15 yr to study relationships between free IGF-I levels and ages, total IGF-I, IGF binding protein (IGFBP)-1, IGFBP-3, and acid-labile subunit (ALS) levels. In both sexes, serum free IGF-I levels and the ratios of free IGF-I to total IGF-I were significantly higher in the pubertal age groups than in the prepubertal age groups. Serum levels of free IGF-I showed a significant positive correlation with those of total IGF-I, IGFBP-3 and ALS, while they showed a significant negative correlation with those of IGFBP-1. These observations suggest that increase in serum free IGF-I levels during puberty is caused by a dramatic increase in total IGF-I, rather than IGFBP-3, and a decrease in IGFBP-1. Also, high free IGF-I levels may play an important role in pubertal growth spurt.     

Quadro-pulse stimulation is more effective than paired-pulse stimulation for plasticity induction of the human motor cortex

OBJECTIVE: Repetitive paired-pulse transcranial magnetic stimulation (TMS) at I-wave periodicity has been shown to induce a motor-evoked potential (MEP) facilitation. We hypothesized that a greater enhancement of motor cortical excitability is provoked by increasing the number of pulses per train beyond those by paired-pulse stimulation (PPS). METHODS: We explored motor cortical excitability changes induced by repetitive application of trains of four monophasic magnetic pulses (quadro-pulse stimulation: QPS) at 1.5-ms intervals, repeated every 5s over the motor cortex projecting to the hand muscles. The aftereffects of QPS were evaluated with MEPs to a single-pulse TMS, motor threshold (MT), and responses to brain-stem stimulation. These effects were compared to those after PPS. To evaluate the QPS safety, we also studied the spread of excitation and after discharge using surface electromyograms (EMGs) of hand and arm muscles. RESULTS: Sizes of MEPs from the hand muscle were enhanced for longer than 75min after QPS; they reverted to the baseline at 90min. Responses to brain-stem stimulation from the hand muscle and cortical MEPs from the forearm muscle were unchanged after QPS over the hand motor area. MT was unaffected by QPS. No spreads of excitation were detected after QPS. The appearance rate of after discharges during QPS was not different from that during sham stimulation. CONCLUSIONS: Results show that QPS can safely induce long-lasting, topographically specific enhancement of motor cortical excitability. SIGNIFICANCE: QPS is more effective than PPS for inducing motor cortical plasticity.     

Impaired cardiovascular autonomic function in Parkinson's disease with visual hallucinations.

We assessed the relations of visual hallucinations (VH) to cardiovascular autonomic dysfunction in patients with Parkinson's disease (PD). The subjects were 37 patients without VH (VH(-)) and 31 with VH (VH(+)). Autonomic function was evaluated on the basis of cardiac 123-radioiodinated metaiodobenzylguanidine (123I-MIBG) uptake and hemodynamic testing with Valsalva maneuver. Systolic blood pressure (SBP) and plasma norepinephrine concentrations (NE) were measured by tilt-table testing. 123I-MIBG uptake was lower in VH(+) than VH(-). Hemodynamic studies showed that VH(-) had only cardiac sympathetic and parasympathetic dysfunction, while VH(+) additionally had reduced vasomotor sympathetic functions. The fall in SBP during tilt-table testing was greater in VH(+) than VH(-). NE and its difference in the supine and upright positions were decreased in VH(+). We conclude that cardiac and vasomotor sympathetic dysfunction is more severe in VH(+) than in VH(-). Severe dysfunction in PD with VH is probably attributed to Lewy-body lesions or neuronal loss in sympathetic ganglia, the central autonomic system, or both.     

Preoperative identification of subthalamic nucleus for deep brain stimulation using three-dimensional phase sensitive inversion recovery technique.

PURPOSE: We assessed the feasibility of utilizing three-dimensional (3D) phase sensitive inversion recovery (IR) images for preoperatively determining deep brain stimulator position. METHODS: We measured geometric distortion with a grid phantom and evaluated images of 3 volunteers to determine optimum imaging parameters for 3D phase sensitive IR. RESULTS: Geometric distortion measured less than 1.0%. Respective inversion and recovery times, which provided high T(1) contrast between the subthalamic nucleus and adjacent tissue, were 200 and 4000 ms. In studies of 3 volunteers and 2 patients, the subthalamic nucleus was clearly depicted in 3D phase sensitive IR images. The measured coordinates of the subthalamic nucleus agreed well with those calculated by conventional estimation from midpoint of the anterior and posterior commissure. CONCLUSION: Three-dimensional phase sensitive inversion recovery was useful in visualizing the subthalamic nucleus for effective deep brain stimulation.     

伊文氏蓝染色对大鼠脑内肿瘤生物学标记方法的研究

目的研究在大鼠脑内肿瘤模型中生物学染色标记脑内肿瘤的方法。方法选择F344大鼠,移植体外培养的RG2胶质瘤细胞制作脑内肿瘤模型,移植18d后经大腿静脉注射伊文氏蓝(Evans blue,EB)染色肿瘤组织,探讨生物学染色对脑内肿瘤的标示作用和手术中对肿瘤和周围正常脑组织鉴别的意义。结果EB浓度在100mg/kg时,肿瘤组织染色成鲜明蓝色,同时大鼠的皮肤和所有器官都被染色成蓝色;当浓度低于10mg/kg时,仅染色肿瘤组织而皮肤和其他器官不被染色;肉眼可鉴别的最低静注浓度为1.25mg/kg。肿瘤组织的染色效果持续到静注后96h。血清中EB浓度在静注后3h内迅速减少,之后呈缓慢代谢过程,静注后24h减少到静注浓度的38%,静注后24h EB在血清和肿瘤组织中的浓度差达到最大值。染色后在手术显微镜下进行肿瘤切除手术操作较未染色对照组明显容易,手术后切片组织学观察肿瘤被完全切除。结论EB生物学染色标记脑内肿瘤效果可靠,手术中作为肿瘤的标示鉴别肿瘤和周围正常脑组织的界限有效。     

Aortic root dilatation may alter the dimensions of the valve leaflets

Objective: Valve-sparing surgery can be used in patients with dilated aortic roots and aortic insufficiency (AI) but has not become a common practice, in part because the spared valve may be incompetent. Our goal was to study how the dimensions of the aortic root and leaflets have changed in such patients. Methods: Fourteen patients with dilated aortic root and AI were examined by transesophageal echocardiography. The annulus diameter, sinotubular junction (STJ) diameter, sinus height, leaflet free-edge length, and leaflet height were measured. Correlations among these dimensions and with the AI grades were explored. Measurements were also made in 19 normal human aortic valves from silicone molds. Results: There was no evident change in the average diameter of the annulus between the normal valves and those in the dilated aortic roots. The STJ diameter was obviously increased in the dilated aortic roots; the aortic sinuses also appeared to be taller and the leaflets larger than normal. The leaflet free-edge length, the leaflet height, and the sinus height were found to increase with the dilated STJ diameter. The degree of AI was not found to correlate well with any of the dimensions measured. Conclusions: The dimensions of the leaflets may change parallel to aortic root dilatation with AI. Therefore, during valve sparing, it may be necessary to correct both the dilatation of the root and the leaflet free-edge length to achieve a competent valve.     

Use of epr oximetry with india ink to measure the po2 in the liver in vivo in mice

The partial pressure of oxygen (pO₂) of the liver in vivo in unanesthetized mice was determined using electron paramagnetic resonance (EPR) oximetry with India ink. The EPR spectra were obtained using a low-frequency (1.2 GHz) EPR spectrometer with a loop gap cavity resonator. The line width of the India ink used in this experiment was reversibly broadened by oxygen and was particularly sensitive to pO₂ below 30 torr. After the administration of India ink into the tail vein, the India ink particles were taken up mainly by Kupffer cells in the liver and in part by phagocytes in the spleen. The pO₂ measured in the normal liver was about 14 torr and was constant for the 2-week experimental period. The pO₂ decreased when measured at 1, 2, and 6 days after treatment with a hepatotoxin (carbon tetrachloride (CCI₄)); within 2 weeks, it returned almost to the initial level. Measurements by EPR at sacrifice of controls and CCI₄-treated mice indicated that more than 90% of the India ink went to the liver; the spleen contained 4.7% of total amount in control mice and 8.8% in CCI₄-treated mice when measured 2 weeks after the treatment. These data indicate the usefulness of India ink for measuring the pO₂ of the liver in vivo and that the pO₂ in the Kupffer cells is decreased when the liver is damaged by CCI₄.     

Mechanism to induce scoliosis in Duchenne muscular dystrophy--a study of paraspinal muscle by X-ray computed tomography]

We studied mechanism to induce scoliosis in Duchenne muscular dystrophy (DMD) by use of X-ray computed tomography (CT) of paraspinal muscles. CT examination of paraspinal muscles was performed on 15 DMD patients at the following six levels; 1. Th3 vertebrae (upper thoracic spine level) 2. Th6 vertebrate (middle thoracic spine level) 3. Th10 vertebrae (lower thoracic spine level) 4. L1 vertebrae (upper lumbar spine level) 5. L3 vertebrae (middle lumbar spine level) 6. L5 vertebrae (lower lumbar spine level). We evaluated the degeneration of paraspinal muscle by a decrease in radio-density of the muscle which indicates infiltration of fatty tissue. The degeneration of the lateral portion of paraspinal muscle was more marked than that of the medial portion. The muscle was most severely affected at the middle lumbar spine level, showing a tendency to increase degeneration at the lower level of the spine. In cases showing laterality of the degeneration of paraspinal muscle, the less affected muscle on CT was located at the convex site of scoliosis. We speculate that the scoliosis occurs when DMD patients have asymmetrical paraspinal muscle degeneration, leading them to take compensatory posture.