View ordering for magnetization prepared steady state free precession acquisition: application in contrast-enhanced MR angiography.

Magnetization prepared segmented acquisition requires a view order that maximizes signal contrast during the acquisition of the central portion of k-space. Steady state free precession (SSFP) acquisition further requires a view order that minimizes changes in phase-encoding gradients from one repetition to the next in order to minimize eddy current artifacts. In this article, optimal view ordering schemes satisfying these two requirements are formulated and applied to inversion prepared 3D SSFP contrast-enhanced MR angiography (MRA). Experiments on phantoms and pigs demonstrated improved background suppression and reduced image artifacts.     

汉防己甲素抑制三种神经递质引起的新生大鼠脑细胞内游离钙的升高

应用Ｐｕｒａ－２技术测定游离新生大鼠脑［Ｃａ２＋］ｉ浓度的技术、研究了Ｔｅｔ对静息脑［Ｃａ２＋］ｉ和３种递质引起的脑［Ｃａ２］ｉ变化的影响。Ｔｅｔ（１，１０和２０μｍｏｌ·Ｌ－１）对静息脑［Ｃａ２＋］ｉ无明显影响。Ｔｅｔ（１０μｍｏｌ·Ｌ－１）可降低Ｌ－Ｇｌｎ（０．１、１．０和１０μｍｏｌ·Ｌ－１）引起的脑（Ｃａ２＋）ｉ的升高。在Ｈａｎｋ＇ｓ液Ｃａ２＋为１．３ｍｍｏｌ·Ｌ－１时，Ｔｅｔ１０μｍｏｌ·Ｌ－１可降低Ｈｉｓ（５０和１００μｍｏｌ·Ｌ－１）和５－ＨＴ（０．１、１．０、１０和１００μｍｏｌ·Ｌ－１）引起的脑［Ｃａ２＋］ｉ的升高。但不能降低Ｈａｎｋ＇ｓ液无Ｃａ２＋时Ｈｉｓ和５－ＨＴ引起的脑［Ｃａ２＋］ｉ的升高。研究表明Ｔｅｔ可阻滞Ｌ－Ｇｉｎ、Ｈｉｓ和５－ＨＴ受体调控的钙通道。但对Ｈｉｓ和５－ＨＴ引起的细胞内贮存钙的释放并无明显影响。Ｔｅｔ的这种降低脑［Ｃａ２＋］ｉ的作用可能是其治疗脑缺血性疾病的机理之一。Ｐ＜０．０１在Ｔｅｔ１０μｍｏｌ·Ｌ－１作用下，相同浓度的细胞外液钙和Ｈｉｓ（０、５０和１００μｍｏｌ·Ｌ－１），脑［Ｃａ２＋］ｉ分别是２２１±５、２４５±５和３０２±６ｎｍｏｌ·Ｌ－１。增加了１１．８?     

1000例正常人发电子自旋共振（ESR）波谱的饱和特性研究

本文报道1000例正常人发自由基的电子自旋共振波谱饱和功率(ESR-SP)的检测结果。所得正常值的全组中位数为2.496mw;95％上下限分别为2.989及1.720mw。如按性别统计,则女性下限(1.617mw)较男性(1.983mw)为低,(P<0.05)。按年龄分别统计,则40岁以上的中位数(2.376mw)及其下限(2.009mw)高于40岁以下的中位数(2.548mw)及其下限(1.597mw),两者差异有显著性(P<0.05)及极显著性(P<0.01)。因此在使用此正常值指标时,必须注意性别与年龄因素。     

Additive effects of earthworm extract with HpD-laser on the enhancement of reactive oxygen production and the inhibition of[~3H]—thymidine.uptake in mouse ascitic tumor cells

The effects of combined use of earthworm extract(912)and HpD-laser on the produc-tion of reactive oxygen and the biosynthesis of DNA in S_(180) tumor cells were studied throughchemiluminescence measurement and[~3H]-TdR incorporation assay.The results showed that as com-pared with the control,the intensity of chemiluminescence emitted by tumor cells treatedsimultaneously with 912 and HpD-laser was enhanced more than ten-folds,while that treated with912 or HpD-laser alone was increased only 2～4 folds.The[~3H]-TdR incorporation into tumorcells of the former group was inhibited upto 74.1%,and that of the latter groups decreased onlyby 42.2% and 40.0%,respectively.In accordance with these biochemical changes,the ultrastructuraldamage of tumor cells of the former,combinedly treated group appeared to be the most serious.This suggests an additive effect of 912 with HpD-laser on tumor cells.In addition,if free radicalscavengers,such as catalase and superoxide dismutase,were added to the reaction systembefore chemiluminescence assay,the luminescent enhancement effect mentioned above was dramaticallyalleviated,implying the presence of O_2~ and H_2O_2 in the system.Therefore,as to the toxic effecton tumor cells,912 and HpD-laser are not only additive in efficiency,but also similar in theunderlying mechanism of action.     

Curative resection of gastric cancer: Limitation of peritoneal lavage cytology in predicting the outcome

Patients with stage T3N0～2M0 gastric carcinoma (n = 108) were studied for relevant prognostic factors. Peritoneal lavage cytology (PLC) was performed in all. In univariate analysis, 5-year survival rates were better with smaller serosal invasion (diameter <3.0 cm vs. ≥3.0 cm, 61% vs. 37%, P < 0.05) and fewer metastatic nodes (≤5 vs. ≥6, 57% vs. 29%, P < 0.05). In multivariate analyses, only these two factors were significant. The predictive value of PLC was not shown in both univariate and multivariate analyses. Peritoneal recurrence occured in 14 (22%) of 77 patients with negative PLC, and in 3 (18%) of 17 with positive PLC, the difference being not significant. Our results indicate that PLC is insensitive in predicting the development of peritoneal recurrence. Its role in the estimation of survival is limited, as many will die of visceral or locoregional recurrence if not of peritoneal dissemination.     

Total and free tissue factor pathway inhibitor in pregnancy hypertension.

OBJECTIVE: To clarify the role played by tissue factor pathway inhibitor (TFPI) in pregnancy hypertension. METHODS: Using enzyme-linked immunosorbent assays, hemostatic measurements were obtained for women with pre-eclampsia (n=51), nonproteinuric hypertension of pregnancy (n=62), postpartum pre-eclampsia 24 h after childbirth (n=31), and no hypertension (healthy pregnant controls, n=100). RESULTS: There was a significant increase in circulating free TFPI levels in women with pre-eclampsia (9.7+/-6.2 ng/mL) or nonproteinuric hypertension of pregnancy (8.3+/-5.3 ng/mL) compared with healthy controls (5.3+/-2.1 ng/mL). In women with pre-eclampsia the levels remained elevated after placental delivery (10.6+/-4.0 ng/mL). Free protein S levels were significantly higher in women with pre-eclampsia (40.0%+/-10.7%), nonproteinuric hypertension of pregnancy (37.1%+/-12.5%), or postpartum pre-eclampsia (39.3%+/-9.1%) than in healthy pregnant controls (32.2%+/-8.5%). CONCLUSION: Increased levels of the physiologically active free forms of TFPI and free protein S, 2 coagulation inhibitors, may protect women with pregnancy-induced hypertension from the risks of hemostatic activation.     

Effects of Dopexamine on Lipid Peroxidation During Aortic Surgery in Pigs: Comparison with Dopamine

OBJECTIVE: We investigated the dose-related effect of dopexamine and dopamine on free radical production and lipid peroxidation estimated by MDA measurements in an ischaemia-reperfusion model of supraceliac aortic repair. DESIGN: Prospective, randomized, blinded experimental study. MATERIALS: Twenty-five healthy pigs. METHODS: All experiments were performed under general endotracheal anaesthesia. Supraceliac aortic cross clamping was performed in all pigs. The pigs were randomly assigned into five groups (n=5 in each group) and received a continuous intravenous infusion of normal saline (CTL), dopamine 2 microg kg(-1)min(-1) (dopa 2), dopamine 8 microg kg(-1)min(-1) (dopa 8), dopexamine 2 microg kg(-1)min(-1) (dopex 2), dopexamine 8 microg kg(-1)min(-1) (dopex 8). Cardiac output, mean arterial pressure, arterial blood gas analysis and blood sampling for plasma MDA measurements (to reveal lipid peroxidation) were recorded after induction of anaesthesia (baseline), 60 and 120 min after cross-clamping of aorta (ischaemia phase), and 60 and 120 min after restoration of flow (reperfusion phase). RESULTS: Dopexamine and dopamine at 8 microgkg(-1)min(-1) reduced MDA at 60 and 120 min after reperfusion. CONCLUSION: Dopexamine seems superior to dopamine in reducing oxygen free radicals and subsequent lipid peroxidation during reperfusion after supraceliac aortic cross clamping in pigs.     

Pathogenesis of progressive muscular dystrophy: studies on free radical metabolism in an animal model

Evidence to suggest the presence of abnormal metabolism of oxygen free radicals in progressive muscular dystrophy is presented using an animal model. In the superficial pectoral muscles of dystrophic chickens, enzyme activities regulating the metabolism of oxygen free radicals, i.e., catalase, superoxide dismutases and glutathione peroxidase, were significantly elevated within 1 week of hatching. Activities of related enzymes, i.e., glutathione reductase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase were also elevated. In contrast, the specific activity of phosphofructokinase, the rate-limiting enzyme of the glycolytic pathway, was normal during the first 4-week period. These results suggest that there is an increased turnover of oxygen free radicals in the dystrophic muscle. This concept appears important in a further investigation of the pathogenesis and treatment of progressive muscular dystrophies.     

缺血－再灌注兔心肌肌浆网自由基的测定

应用电子自旋共振波谱仪（ＥＳＲ）直接检测了缺血－再灌注兔心肌肌浆网自由基的变化，以探讨肌质网系统与氧自由基的关系。实验中将２０只兔随机分为再灌注对照组、超氧化物歧化酶（ＳＯＤ）组、ＡＴＰ－氯化镁组和人参皂甙Ｒｅ组。实验结果，ｇ值２．００４６处为半醌自由基波谱，其相对浓度各组依次为７８．９４±２．１２６，１４．４６±２．８６，２０．６５±７．６５，１４．６６±３．６７（ｘ±ＳＤ），对照组与用药组均有显著性差异（Ｐ＜０．０５），表明缺血－再灌注兔心肌肌浆网产生大量的自由基，用ＥＳＲ可以直接检测到半醌自由基，外源性高能磷酸盐制剂ＡＴＰ－氯化镁及人参皂甙Ｒｅ与超氧化物歧化酶一样，发挥清除兔心肌肌浆网自由基的作用。     

Physiological consequences of a high work of breathing during heavy exercise in humans

The healthy respiratory system has a remarkable capacity for meeting the metabolic demands placed upon it during strenuous exercise. For example, in order to regulate alveolar partial pressure of oxygen and carbon dioxide during heavy workloads, a 20-fold increase in alveolar ventilation can occur. The high metabolic costs and subsequent increased work of breathing associated with this ventilatory increase can result in a number of limitations to the healthy respiratory system. Two examples of respiratory system limitations that are associated with a high work of breathing are expiratory flow limitation and exercise-induced diaphragmatic fatigue. Expiratory flow limitation can lead to an inability to increase alveolar ventilation () in the face of increasing metabolic demands, resulting in gas exchange impairment and diminished endurance exercise performance. Furthermore, the high ventilatory requirements of endurance athletes and the inherent anatomical differences in females could make these groups more susceptible to expiratory flow limitation. Fatigue of the diaphragm has also been documented after strenuous exercise and may be related to a mechanism which increases sympathetic vasoconstrictor outflow and reduces limb blood flow during prolonged exercise. This competition between the muscles of respiration and locomotion for a limited cardiac output may have dramatic consequences for exercise performance. This brief review summarizes the literature as it pertains to the work of breathing, expiratory flow limitation, and exercise-induced diaphragmatic fatigue in healthy humans.