氯化四乙基铵及维拉帕米对家兔缺血心肌不应期的影响

实验比较了K⁺通道阻断剂氯化四乙基铵(TEA)及Ca²⁺通道阻断剂维拉帕米(verapamil,Ver)对家兔缺血性心室肌不应期(ERP)的影响。结果表明,阻断冠脉10min及30min后,缺血中心区(CIZ)和缺血边缘区(BIZ)心肌ERP比缺血前均明显缩短,而TEA和Ver均能延长急性缺血性心肌的ERP,可能对心肌缺血引起的心律失常有预防作用。     

Magnetic resonance imaging: absence of in vitro cytogenetic damage

Human lymphocytes and Chinese hamster ovary (CHO) cells in culture were exposed for 12 1/2 hours to a magnetic resonance imaging apparatus with a 2.35-Tesla magnet and 100-MHz radio frequency emission. The cells were examined for cytogenetic damage manifested either as chromosome aberrations or sister chromatid exchanges (SCEs), which constitute very sensitive measures of genetic and cellular damage. In either unstimulated or stimulated human lymphocytes, as well as in exponentially growing CHO cells, no increase in either chromosome aberrations or SCEs was found as a result of exposure to these MR conditions. The data indicate that long-term exposure to MR imaging conditions far exceeding those to be found in the clinical situation does not cause cytogenetic damage.     

Permanent inflation of detachable balloons with a low-viscosity, hydrophilic polymerizing system

A polymer system was developed for use in permanent inflation of detachable balloons, to avoid long-term reliance on the integrity of balloon shells or valve mechanisms. This system is based on 2-hydroxy-ethyl methacrylate (HEMA) as the monomer, in combination with a cross-linking agent and a water-soluble curing system. The low-viscosity, hydrophilic mixture can be exchanged through a small-bore catheter into a detachable balloon and polymerizes in 40-60 minutes at body temperature. Partially polymerized HEMA can cause vascular occlusion; hence, careful timing of balloon detachment is required. The evolution of the radiographic appearance of HEMA-filled balloons is predictable. The balloons remain radiopaque on plain radiographs as long as the balloon shell and valve mechanisms are competent. After rupture of the shell or failure of the valve mechanism, the balloons become invisible on plain radiographs but remain hyperattenuating on computed tomography scans.     

Platelet 3H-imipramine binding and sulphotransferase activity in primary headache

We investigated platelet ³H-imipramine (³H-IMI) binding, a putative peripheral serotonergic marker, and the activity of sulphotransferase (ST), an enzyme involved in the catabolism of catecholamines and phenolic compounds, in 14 patients suffering from migraine without aura (MWoA) and in 10 with tension-type headache (TH), as compared with a group of controls. The possible relationships between the biological parameters and clinical features were also examined. The results showed that the two groups of patients had a lower number of ³H-IMI binding sites and a lower activity of the thermolabile form of ST, which acts preferentially on monoamine substrates, than the healthy controls, with no intergroup differences. Significant correlations between psychopathological rating scales and characteristics of the illness were observed in the patients with TH. The decreased number of platelet ³H-IMI binding sites is suggestive of a presynaptic serotonergic dysfunction and confirms the involvement of 5HT in primary headaches. The reduced ST activity might produce changes in the level of sulphated biogenic amines, including dopamine and tyramine, which might have an additional role in the pathophysiology of some aspects of primary headache.     

Application of image-guided surface coil P-31 MR spectroscopy to human liver, heart, and kidney

Localized phosphorus-31 magnetic resonance (MR) spectroscopy in humans has previously been accomplished with surface coils by means of depth-resolved surface coil spectroscopy or rotating frame experiments, in which the extent of tissue sampled critically depends on surface coil placement. The authors' goal was to modify the surface coil image-selected in vivo spectroscopy (ISIS) experiment to accomplish three-dimensional volume selection through application of selective pulses in the presence of B0 gradients. Advantages of ISIS include the ability to use proton images to define the volume of interest (VOI) and reduced dependence on exact positioning of the surface coil. However, rapid replication of the surface coil ISIS experiment can cause spectral contamination from signals originating outside the VOI. A modified version of the ISIS experiment was developed to alleviate contamination under conditions of rapid replication. Applications of localized P-31 MR spectroscopy for observation of high-energy phosphorus metabolites are presented in human liver, heart, and transplanted and normal kidney.