Magnetic resonance imaging of the rat brain following acute carbon monoxide poisoning.

Magnetic resonance (MR) may be used for repeatedly and non-invasively imaging the brain. Until now, no studies have used this approach to study the effects of carbon monoxide (CO) poisoning in a defined animal model. Conscious, Levine-prepared female rats (unilateral carotid artery and jugular vein occlusion) were exposed to 2400 ppm CO for 90 min, with or without the infusion of 50% glucose solution; CO-stimulated increases in blood glucose and lactate occurred in both groups, while blood pressure and body temperature fell. One to four hours following termination of CO exposure, increased cortical pixel intensity, cortical surface area and brain midline shift were observed on the operated side of the brain in some rats of both groups (i.e. responders = R), providing evidence of edema. At sacrifice, 5 h following termination of CO exposure, gross water content was increased on the left side in the corresponding cortical slices in R rats, providing another measure of edema. Significant positive correlations were found between left to right pixel intensity difference and water content difference, and between the extent of midline shift and water content difference. The elevations of blood glucose and lactate concentrations, and the magnitudes of CO-induced hypothermia and hypotension were similar to those in past studies, but appeared to exert no effect on the severity of cortical edema in terms of differences in pixel intensity, surface area, midline shift or gross tissue water content. Thus, the observed differences between the R rats is not explained by the available data.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects on the offspring of chronic low exposure carbon monoxide during mice pregnancy.

This research is primarily concerned with the effects of chronic low doses of carbon monoxide on fetal development. Carbon monoxide was administered daily by inhalation to female Swiss Webster mice from the beginning of gestation until term. Daily weights were recorded and carbon monoxide blood levels determined every 4 days. The number of offspring in each litter was recorded. At weaning, two males and two females from each litter were randomly picked for maze running studies. When the mice were 6 weeks old, they were tested daily, ten trials per day, in the maze until learning had occurred. The number of days required to learn the maze and the number of incorrect trials were recorded. While there was no significant increase in the number of days needed to learn the maze, there was a significant increase in the number of errors made by the experimental group during this time. This indicated that an increased effort was needed to learn the maze.     

Quality assessment of unfractionated heparin using 1H nuclear magnetic resonance spectroscopy

Due to problems, especially anaphylactoid reactions, raised by impure unfractionated heparin the quality assessment of heparin has to be reconsidered. Neither the USP nor the European Pharmacopoeia are able to guarantee the purity of heparin, i.e., the limitation of oversulfated chondroitin sulfate (OSCS) which was found to be the reason for the allergic adverse effects. In the first run the regulatory authorities ask for (1)H NMR spectroscopic and capillary electrophoretic measurements in order to characterize the impurity profile of heparin. Using an optimized (1)H NMR method the limit of detection for OSCS was found to be 0.1%. In addition, it is possible to reliably quantify both OSCS and dermatan sulfate (DS), the latter being an indicator of poor purification of the unfractionated heparin. Screening of more than 100 heparin samples collected from international markets revealed a high number of samples containing substantial amounts of DS and a number of samples containing OSCS in an amount higher than 0.1%.     

Principles and applications of nuclear magnetic resonance imaging

The physics, instrumentation, and general aspects of nuclear magnetic resonance (NMR) imaging are discussed. NMR images are constructed from magnetic signals emitted by certain atomic nuclei when they are subjected to simultaneously applied magnetic fields and externally generated radiofrequency (r.f.) energy. Hydrogen (the nucleus of which is a single proton) is sensitive to NMR and sufficiently abundant in tissues to produce the signals necessary for image formation. The NMR imaging device consists of a large magnet, a radiofrequency-transmitter coil, and computer hardware. Following r.f. pulsing, the strength and origin of the magnetic signals can be determined by magnetic field gradients that are superimposed on a magnetic field. Then this spatial information can be encoded electronically and reconstructed into a cross-sectional image. NMR imaging is valuable for the diagnosis of a variety of diseases and traumas since a high level of lesion and soft tissue contrast is possible in most types of pathology. Compounds containing paramagnetic elements (magnetopharmaceuticals) may be useful to enhance tissue contrast and organ detail. The high level of tissue detail, sensitivity to pathology, and apparent lack of hazard make NMR an important addition to the existing diagnostic modalities.     

功能性脑成像技术在海洛因依赖研究中的应用

20世纪90年代以来,脑成像技术逐渐被引用来观察成瘾过程中脑内受体的上调、下调,受体亲和力,脑内递质的变化,糖和氨基酸等代谢的变化.它不仅可以用来分析躯体依赖时的变化,也可以分析精神依赖时的变化[1].     

The response of the rat liver in situ to bromobenzene--in vivo proton magnetic resonance imaging and 31P magnetic resonance spectroscopy studies

Proton magnetic resonance imaging (MRI) and 31P magnetic resonance spectroscopy (MRS) have been used to study the response of the rat liver in situ to bromobenzene, a classic hepatotoxicant. A localized region of high proton signal intensity was seen in the perihilar region of the liver 24 hr after injection of a sublethal dose of bromobenzene. The signal intensity of the entire liver was increased at 48 hr with a gradual return approaching control values by 120 hr. These results are consistent with acute hepatic edema followed by repair of the damaged tissue. In vivo 31P MRS studies of the same rat livers were performed under conditions whereby localized, quantitative spectra could be obtained without surgical intervention. Initial concentrations of the major endogenous phosphorus-containing metabolites within the livers of control rats were 2.97 +/- 0.43 mM for the phosphomonoesters (PME), 2.92 +/- 0.56 mM for inorganic phosphate, 11.3 +/- 1.0 mM for phosphodiesters (PDE), 4.09 +/- 0.54 mM for ATP, and 0.56 +/- 0.50 mM for ADP and the intracellular pH was 7.39 +/- 0.14 (mean +/- SD, n = 10). Bromobenzene was found to cause statistically significant (p less than 0.05) changes in several of these metabolites: a decrease in hepatic ATP levels (20% at 24 hr; 27% at 48 hr), a decrease in PDE levels (15% at 24 hr; 18% at 48 hr), and an increase in the PME (63% at 24 hr; 84% at 48 hr). Both the proton MRI and the 31P MRS changes have an onset of 15-20 hr and maximum effect at 25-60 hr, but the MRS changes returned to normal well before the MRI changes. The decreased ATP levels indicate deleterious effects of bromobenzene on the bioenergetic status of the liver in situ, while the increase in PME, due to a selective increase in phosphocholine, suggests the activation of a phosphatidylcholine-specific phospholipase C in response to tissue damage. Trolox C, a potent inhibitor of lipid peroxidation, prevented the bromobenzene-induced hepatic edema (i.e., the increase in proton MRI signal intensity) and the bioenergetic deterioration (i.e., the decrease in ATP levels). However, the bromobenzene-induced increase in PME levels was not prevented by Trolox C. These results indicate that the process of lipid peroxidation plays a significant role in the hepatotoxicity of bromobenzene within the intact animal.     

Ischemic tolerance of the heart by adaptation to chronic hypoxia is suppressed by high subchronic carbon monoxide exposure

This study was designed to investigate whether exposure to carbon monoxide (CO) could alter the ischemic tolerance induced by chronic hypoxia. We aimed to determine whether chronic hypoxia-induced cardiovascular adaptation was modified during the return to normoxia or by subchronic CO exposure. The degree of resistance to an in vitro transient ischemia was measured, using the Langendorff method, in hearts from rats previously exposed to chronic hypoxic hypoxia and/or subchronic CO exposure to 600 ppm. Chronic hypoxia decreased ischemic contracture (15.6 +/- 04.9 vs. 60.8 +/- 07.7%) and improved both contractile recovery (59.6 +/- 07.3 vs. 21.8 +/- 06.8%) and ventricular arrhythmia during reperfusion (0 vs. 45%) compared to a control normoxic group. However, in our chronic hypoxia regression model many parameters returned near to control values except for the persistence of cardiomegaly, a significant decrease in both ischemic contracture (22.0 +/- 04.9 vs. 60.8 +/- 07.7%), and ventricular tachycardia (25 vs. 45%). CO exposure alone increased the coronary flow and improved both contractile recovery (42.6 +/- 7.2 vs. 21.8 +/- 6.8%) and ventricular arrhythmia (16.7 vs. 45%) without altering the action potential shape. These two models causing tissue hypoxia induced the same degree of polycythemia or cardiomegaly and provided similar ischemic tolerance. CO exposure after chronic hypoxia exacerbated ischemic contracture (69.3 +/- 10.5 vs. 22.0 +/- 14.5%) and ventricular tachycardia incidence (100 vs. 50%) but with significant alteration in contractile recovery (12.7 +/- 10.5%) compared to the chronic hypoxia or CO exposure. Thus, CO exposure completely suppressed the chronic hypoxia-induced ischemic tolerance.     

磁共振成像的技术发展与临床应用

磁共振成像技术于1973年开始有人报道,1981年用于临床。近年来,磁共振新技术的开发十分迅速,其诊断价值已获得医学界极高的评价。随着MR设备的快速发展、软件功能等新技术的开发以及特异性对比剂的研制,使其逐步改变了以形态学为主的现状,而向生理、功能、代谢和基因成像过渡,对比增强向特异性组织和疾病方向发展。 现代医学的发展要求对疾病能够早期诊断,影像设备及其配套技术也正是基于这种需求而在快速改进和提高。目前开发的磁共振新技术较常规磁共振有了更多的优越性,比如它能够发现超急性期的脑梗死,能     

磁共振成像的技术发展与临床应用

磁共振成像技术于1973年开始有人报道,1981年用于临床.近年来,磁共振新技术的开发十分迅速,其诊断价值已获得医学界极高的评价.随着MR设备的快速发展、软件功能等新技术的开发以及特异性对比剂的研制,使其逐步改变了以形态学为主的现状,而向生理、功能、代谢和基因成像过渡,对比增强向特异性组织和疾病方向发展.     

Effect of acute carbon monoxide exposure on cardiopulmonary function of the awake rat

Unanesthetized male Sprague-Dawley rats were exposed for 20 min to 0 (control), 2000, or 4000 ppm carbon monoxide, and cardiopulmonary responses were evaluated. Venous blood samples were taken prior to exposure and at 2, 4, 7, 11, 15, and 20 min during exposure. Responses for CO-exposed animals were compared at 20, 30, 40, 50, and 60% carboxyhemoglobin (COHb), and these values were compared to control values at similar times during exposure. Fifty percent COHb was attained within 4 to 8.5 min at 4000 ppm and 11 to 14 min at 2000 ppm. For both CO exposure groups, mean arterial pressure first decreased at 40% COHb and fell to 69% of baseline at 60% COHb. Tidal volume and breathing frequency increases resulted in minute volume elevations of 52 (2000 ppm) and 77% (4000 ppm) at 60% COHb. Minute volume was elevated at 50 and 60% COHb at 4000 ppm, but was not elevated until 60% COHb for 2000-ppm exposures. The earlier ventilatory stimulation at 4000 ppm may have been a by-product of increased agitation observed in rats exposed to the higher concentration.     

The complex analytical method for assessment of passive smokers' exposure to carbon monoxide

Carbon monoxide (CO) is one of the toxic constituents in tobacco smoke. The aim of the study was to evaluate a complex analytical method that allows quantification of the exposure of passive smokers to CO. The exposed volunteers were placed in the model room where portions of cigarettes (5, 10, or 15 cigarettes every 30 or 60 min over 4 h) were smoked using a homemade smoking machine. The concentrations of CO and of the ventilation marker (methane) were monitored for the duration of each experiment. CO and methane were analyzed on-line using GC-FID with methanization. Carboxyhemoglobin (COHb) was analyzed twice: just before and after the experiment. After hemolysis of a 100-microL blood sample, CO was quantitatively released by adding 10% K3[Fe(CN)6] inside a small reactor and under stable pressure transported through a microtube with an absorbing agent on a chromatography loop. The proposed analytical method allows us to quantify exposure of passive smokers by measuring the dose-effect correlation. We observed that increasing COHb levels were directly correlated with the CO concentration in the air, but were also intermediately correlated with the frequency and number of smoked cigarettes and with the ventilation coefficient.     

In situ, real time observation of the disintegration of paracetamol tablets in aqueous solution by magnetic resonance imaging.

The disintegration behavior of paracetamol tablets was studied by magnetic resonance imaging (MRI) using the Snapshot FLASH method. The total time of the single experiment is 425 ms and allows the study of the disintegration process in real time. The study was carried out in vitro under acidic gastric pH conditions and may help to predict the behavior of paracetamol tablets in the stomach after oral administration. It was shown that in spite of identical conditions, the disintegration of the tablets under study was different. The distribution of protons of 4-(N-acetyl)aminophenol within the paracetamol tablet was shown to be homogeneous. The study was carried out in a non-destructive way by the SPI MRI method.     

对比增强核磁共振技术对颈动脉易损斑块的评估价值

目的:探讨对比增强核磁共振成像技术(contrast-enhanced magnetic resonance imaging,CEMRI)对颈动脉易损斑块的评估价值.方法:对普通二维多普勒超声检查发现颈动脉斑块并且血管狭窄程度>50%者,进一步行CEMRI检查,记录并分析检查结果.结果:共计76名患者进行了CEMRI检查(其中男性53例,女性23例),59例(77.6%)患者发现易损斑块,总易损斑块数为135个.其中脂质坏死核59个,有钙化斑块46个,斑块内出血30个.结论:CEMRI技术可以显示颈动脉斑块结构特点及成分特征,客观评价斑块的稳定性.     

磁共振成像在肛瘘术前评估的临床价值

目的 探讨磁共振成像(MRI)在肛瘘术前评估的临床价值.方法 选择本院2014年3～12月收治的89例临床疑为肛瘘的患者为研究对象,所有患者术前均接受MRI检查.结果 MRI检查的诊断率较高;3D SPGRT1WI序列对内口及主瘘管的显示率高于其他扫描序列(AX T2WI FS除外)及术前临床专科检查(P＜0.05).3DSPGR T1WI序列对支瘘管的显示率高于其他扫描序列及术前临床专科检查比较(P＜0.05).结论 MRI是一种较为可靠的肛瘘术前检查方法,具有较高的推广应用价值.     

Examining the neural targets of the AMPA receptor potentiator LY404187 in the rat brain using pharmacological magnetic resonance imaging

Rationale Drugs that enhance α-amino-3-hydroxy-5-methyl-4-isoxazolepropanoic acid (AMPA) receptor-mediated glutamatergic transmission, such as the AMPA receptor potentiator LY404187, may form treatment strategies for disorders of cognition, learning and memory. Objectives Pharmacological magnetic resonance imaging (phMRI) uses blood oxygenation level dependent (BOLD) contrast as a marker of neuronal activity and allows dynamic non-invasive in vivo imaging of the effects of CNS-active compounds. This study used phMRI to examine the effects of LY404187 in the rat brain. Method Groups of Sprague Dawley rats (n=7) were anaesthetised and placed in a 4.7 Tesla superconducting magnet before receiving an acute dose of LY404187 (0.5 mg/kg s.c.), either alone or after pretreatment with the selective AMPA/kainate antagonist LY293558 (15 mg/kg s.c.), or LY293558 alone (15 mg/kg s.c.). Brain images were acquired for each subject every minute for 180 min. These volumes were extensively pre-processed before being analysed for changes in BOLD contrast. Results LY404187 produced significant increases in BOLD contrast in brain regions including the hippocampus, lateral and medial habenulae and superior and inferior colliculi. These changes were blocked by LY293558. When administered alone, LY293558 caused widespread decreases in BOLD contrast. Conclusions The known actions of LY404187 suggest the observed BOLD signal increases reflect increases in excitatory neurotransmission. The decreases in signal following LY293558 alone are harder to interpret and are discussed in terms of the negative BOLD response. This study provides the first evidence that the effects of AMPA receptor-mediating compounds can be observed using phMRI.     

Magnetic resonance imaging and magnetic resonance spectroscopy assessment of brain function in experimental animals and man

This paper introduces the basic principles and techniques of functional magnetic resonance imaging (fMRI) and spectroscopy (MRS). Examples are given of single event human fMRI studies on control subjects, and a graded activation protocol applied to Parkinsonian patients. Possibilities are discussed for using fMRI techniques to study the neural substrate of various pharmacological agents, including drugs of abuse. The application of these pharmacological MRI (phMRI) studies to animal models and the associated technical issues are also addressed. The use of MRS in studying brain status and function is reviewed, with particular emphasis on 13C isotopic labelling studies.     

哺乳期乳腺癌磁共振影像诊断的价值研究

目的 探讨磁共振在哺乳期乳腺癌的价值及可行性.方法 回顾性分析2014年8月至2021年1月我院诊治的26例经手术病理诊断的哺乳期乳腺癌患者的磁共振影像特点及临床资料.结果 26例哺乳期乳腺癌患者中,MRI诊断出乳腺癌26例,浸润性导管癌23例,浸润性小叶癌2例,导管内癌1例,所有病例经病理证实,MRI与临床病理诊断符合率为100％.结论 磁共振诊断哺乳期乳腺癌价值较高,检出率高,值得临床应用及推广.     

Disruption of neostriatal development in rats following perinatal exposure to mild, but chronic carbon monoxide

The vulnerability of the developing neostriatum to mild, but chronic hypoxia was evaluated in weanling rats exposed only in utero or from conception through postnatal day 10 to 0, 75, 150, and 300 ppm carbon monoxide (CO). The exposure conditions produced maternal carboxyhemoglobin (HbCO) levels of about 11, 19, and 27 percent. HbCO levels of 5 percent are maintained by human cigarette smokers while comparable levels in non-smokers average less than 1%. Significant elevations in DNA and the neurotransmitter, dopamine (DA), were observed in the striatum of 21-day-old rats following the combined pre- and neonatal CO exposure. These neurochemical changes were observed 11 days after CO exposure was terminated and, therefore, cannot be interpreted as acute responses to reduced oxygen. These data indicate that the immature neostriatum is altered by even mild hypoxic insults presented during the time of neuronal proliferation and synaptogenesis.     

1H nuclear magnetic resonance study of metronidazole metabolism by perfused rat liver

High-resolution 1H nuclear magnetic resonance (NMR) spectroscopy at 300 MHz has been used to monitor the metabolism of metronidazole by the perfused rat liver. Samples of perfusate removed at various times during the perfusion show resonances from metronidazole and its major metabolites, as well as those from organic metabolites released from the liver. The major metabolite of metronidazole is shown to be its glucuronide conjugate. Metronidazole metabolism and glucuronide production are both stimulated in livers from rats pretreated with phenobarbitone.