Cardiac metabolism: A technical spectrum of modalities including positron emission tomography,single-photon emission computed tomography,and magnetic resonance spectroscopy

Noninvasive techniques for the assessment of cardiac metabolism are important for the detection of potentially salvageable tissue in jeopardized areas of the myocardium. The correct identification of hibernating and stunned myocardium in patients with severely depressed cardiac function can have vital therapeutic consequences for the patient. Changes in myocardial fatty acid and glucose metabolism during acute and prolonged ischemia can be traced by positron-emitting or gamma-emitting radiopharmaceuticals. Alternatively,³¹P-labeled magnetic resonance spectroscopy can be used for the assessment of high-energy phosphate metabolism. It is not yet clear which modality will emerge as the most useful in the clinical setting. Positron emission tomography (PET) that uses combinations of flow tracers and metabolic tracers offers unique opportunities for quantification and high-resolution static and rapid dynamic studies. Currently, assessment of glucose metabolism with¹⁸F-fluorodeoxyglucose is regarded as the gold standard for myocardial viability and prediction of improvement of impaired contractile function after revascularization. However, preserved oxidative metabolism may be required for potential functional improvement, and therefore assessment of residual oxidative metabolism by¹¹C-labeled acetate PET may prove to be more accurate than¹⁸F-fluorodeoxyglucose PET, which reflects both anaerobic and oxidative metabolism. Moreover, because fatty acids are metabolized only aerobically, they are excellent candidates for the clinical assessment of myocardial viability and prediction of functional improvement after revascularization. Especially derivatives of fatty acids that are not metabolized but accumulate in the myocyte are attractive for myocardial imaging. Examples are¹²³I-beta-methyl-p-iodophenyl pentadecanoic acid and 15-(o-¹²³I-phenyl)-pentadecanoic acid. These tracers can be detected by planar scintigraphy and single-photon emission computed tomography, which are more economical and widely available than PET. In addition, 511 keV collimators have been developed recently, making the detection of positron emitters by planar scintigraphy and single-photon emission computed tomography feasible. The experience with³¹P-labeled magnetic resonance spectroscopy in humans is still limited. With current magnetic resonance spectroscopic techniques, insufficient spatial resolution is achieved for clinical purposes, but the possibility of serial measurements to monitor rapid changes of phosphate-containing molecules in time makes magnetic resonance spectroscopy very valuable for the research of myocardial metabolism.     

小柴胡汤口服液药效作用的研究

观察了小柴胡汤口服液的主要药理作用。研究表明,小柴胡汤口服液有显著抑制角叉菜胶诱发的大鼠踝关节水肿(p<0.05),保护四氯化碳所致的大鼠急性肝功能损害,有极显著降低血清SGPT及LDH的作用(P<0.01)。对家兔发热反应也有较好的抑制作用。此外,小柴胡汤口服液对小鼠兔疫反应也有一定的增强作用,可促进小鼠碳粒廓清速率,提高血清溶血素水平及增强鸡红细胞所致的迟发性过敏反应。     

羧基化多壁碳纳米管修饰电极伏安法测定多巴胺

目的 :研究用羧基化多壁碳纳米管修饰电极伏安法测定痕量多巴胺 (DA)的效果。方法 :采用涂布法制成羧基化多壁碳纳米管修饰电极 ;在pH =5 .4的KH2 PO4 Na2 HPO4缓冲溶液中 ,采用该修饰电极伏安法测定DA。结果 :该修饰电极对DA有着显著的电催化作用 ,与裸玻碳电极相比较 ,其灵敏度大大提高 ,在2 .0× 10 -7～ 6 .0× 10 -4mol/L浓度范围内 ,DA的氧化峰电流与浓度成良好的线性关系 ,检测限为 5 .0× 10 -8mol/L。将该修饰电极用于盐酸多巴胺针剂的测定 ,相对平均偏差为 1.4 % ,平均回收率为 99.2 %。结论 :该修饰电极响应快 ,灵敏度高 ,稳定性好 ,寿命长 ,适合于具有电活性生物分子的测定     

Cerebral perfusion assessment by bolus tracking using hyperpolarized 13C.

Cerebral perfusion was assessed with 13C MRI in a rat model after intravenous injections of the 13C-labeled compound bis-1,1-(hydroxymethyl)-1-13C-cyclopropane-D8 in aqueous solutions hyperpolarized by dynamic nuclear polarization (DNP). Since the tracer acted as a direct signal source, several of the problems associated with techniques based on traditional dynamic susceptibility contrast (DSC) MRI contrast agents were avoided. Maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were calculated. The MTT was determined to be 2.8 +/- 0.8 sec. However, arterial partial-volume effects in the animal model prevented accurate absolute quantification of CBF and CBV. It was demonstrated that depolarization of the hyperpolarized 13C tracer via relaxation and the imaging sequence had little influence on CBF assessment when the time resolution of the imaging sequence was short compared to the MTT. However, CBV and MTT were increasingly underestimated as MTT or the depolarization rate increased if depolarization was not taken into account. With a modified bolus-tracking theory depolarization could be compensated for, assuming that the depolarization rate was known. Three separate compensation methods were investigated experimentally and by numerical simulations.     

一项新的水质检验——可同化有机碳测定

可同化有机碳(AOC)是一项新的水质检测指标,通过它可以评估供水系统的水中是否有足够的营养物质可使微生物再生长。由于目前尚无可行的化学方法检测 AOC,因此主要是用各种生物方法加以检测。本文介绍用荧光假单胞菌 P—17菌株和螺菌属 NOX 菌株作为测试菌,通过定量观察其在水样中的生长,如从接种到生长至最大数量,以考察其利用水中营养物质的情况,进而推算出水中 AOC 的浓度。     

Fresh gas flow in the Bain circuit during laparoscopy

Twenty-two women were studied during laparoscopy with abdominal insufflation of carbon dioxide. A bain anaesthetic breathing circuit was used with a fresh gas flow (VFG) of 110 ml.min-1.kg-1, and controlled ventilation was applied with a minute ventilation (VE) of 175 ml.min-1.kg-1. Arterial blood gases were analysed at the end of the operation. Nineteen of the women (86 per cent) were found to have a PaCO2 within the range for normocapnia (i.e., 4.7-5.9 kPa (35-45 mmHg), two were hypocapnic with a PaCO2 of 4.4 and 4.5 kPa (33 and 34 mmHg) respectively and one was found to have a PaCO2 of 6.2 kPa (46.5 mmHg). It was concluded that the carbon dioxide absorbed from the abdomen during laparoscopy demands fresh gas flows that are higher than normally used in the Bain circuit if a PaCO2 within the normal range is to be obtained. A simultaneous increase in VFG and VE of about 45 per cent is sufficient to achieve normocapnia.     

Effect of chronic carbon tetrachloride poisoning on the turnover of RNA fractions in rat liver tissue

Changes in the content and incorporation of 5-³H-uridine after brief exposure to its labeled precursor were studied in the individual liver RNA fractions of rats during administration of carbon tetrachloride for 24 weeks. These fractions were obtained by preparative electrophoresis in 2.5% polyacrylamide gel from previously isolated nuclear and cytoplasmic RNA. Administration of CCl₄ to rats was shown to reduce the quantity of transfer and ribosomal RNA in the liver tissue. Chronic CCl₄ poisoning also disturbs the synchronization of the turnover of the individual components of fast-labeled RNA.Laboratory of Biochemistry, Professor N. N. Petrov Scientific-Research Institute of Oncology, Ministry of Health of the USSR, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR S. N. Golikov). Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 423–425, April, 1977.     

一氧化碳保护大鼠肠道对抗LPS的作用机制

目的： 探讨外源性CO对LPS攻击时大鼠肠道的保护作用及作用机制。 方法： 血气分析监测大鼠呼吸参数，在1、3、6 h的时点上，分别对空白组、脂多糖组（LPS，5 mg/kg）、低浓度CO吸入组（CO 250 mL/M3）、腹腔内CO注射组（CO 2 mL/kg）、脂多糖CO吸入组（LPS 5 mg/kg+CO 250 mL/M3）和脂多糖血症CO腹腔内注射组（LPS 5 mg/kg+CO 2 mL/kg），用硫代巴比妥酸法（TBA）测定肠道丙二醛（MDA）含量，用羟胺法测定超氧化物歧化酶（SOD）活性，并应用RT-PCR检测肠道组织内的血红素氧合酶-1（HO-1）mRNA的变化。 结果: 给予250 mL/M3的CO持续吸入以及2 mL/kg的CO腹腔内注射，在1、3、6 h时点上，大鼠无缺氧情况的出现。两种方法给予外源性的CO，均降低了内毒素血症时大鼠肠道组织中的MDA含量，提高了SOD的活性，同时诱导了肠组织的HO-1 mRNA 的表达。 结论: 低浓度的CO吸入（250 mL/M3）和一次性腹腔内注射CO（2 mL/kg）补充对大鼠是安全的，补充低浓度或小剂量的外源性CO可以对脂多糖血症肠道提供保护作用，并可以刺激HO-1的产生，促进内源性的CO产生发挥抗炎作用。