医院数字减影设备质量控制的探索与研究

目的定期检测数字减影血管造影（DSA）设备的主要性能指标,并从检测数据中得出规律性因素,从而保证设备的良好性能。方法选取同一厂家相同型号的两台DSA,按照我院2007《中国人民解放军总医院DSA质量检测技术规范》进行质量检测,并对其检测数据运用独立样本t验统计分析。结果两台DSA设备由于所处工作负荷状态不同,其空气比释动能率、管电压精度等检测项目差异有统计学意义（P〈0.01）。结论质量检测是质量控制的重要环节,通过对检测数据进行统计分析,有助于评估设备运行的实际工作状态,并及时发现问题,有针对性的处理解决。     

Cytoskeletal changes in rat cortical neurons induced by long-term intraventricular infusion of leupeptin

Neurofibrillary tangles (NFTs), which are composed of paired helical filament (PHF)-like filaments, were induced by the long-term intraventricular infusion of leupeptin, a potent protease inhibitor. The fibrils composing the NFTs were 20 nm in maximal width and had periodic constrictions at 40-nm intervals. They were identical to the PHF that had been found in aged rat neurons. Dystrophic axons filled with mainly tubular structures were also abundantly found in the parietal and temporal isocortices, which were not affected in the acute or subacute phases of leupeptin treatment. An immunohistochemical study using antibodies related to the neuronal cytoskeleton showed that neuronal cytoskeletal changes accompanying ubiquitination occurred in dystrophic axons distributed widely in the isocortex as well as the hippocampal formation. The present findings suggest that long-term administration of leupeptin accelerates the neuronal ageing process in rats and causes other neuronal changes: NFT formation, such as seen in the aged brain or in neurodegenerative diseases including Alzheimer's disease, in addition to accumulation of lipofuscin granules and degeneration of neuronal processes. In other words, some disturbance of the balance between proteases and their inhibitors may play an important role in the neuronal ageing process, and some regulatory intervention in the intraneuronal protease activity may provide a new therapeutic strategy for the neurodegenerative diseases.This study was presented in part at the Third International Congress on Alzheimer's Disease and Related Disorders at Padova in July 1992     

Ubiquitin immunoreactivity of paired helical filaments differs in Alzheimer’s disease and corticobasal degeneration

To establish whether there is a relationship between ubiquitination and ultrastructural appearance of filaments, we compared the ubiquitin immunoreactivity of paired helical filaments (PHFs) in Alzheimer’s disease (AD) and corticobasal degeneration (CBD). PHFs in these disorders share a limited similarity since filaments in CBD are wider and twisted at longer intervals than those in AD, and also display less ultrastructural stability. Preparations enriched in SDS-soluble filaments were isolated from AD and CBD brains and subjected to tau and ubiquitin immunogold labeling. Both preparations contained mostly dispersed individual PHFs, which labeled for the amino and carboxyl termini of tau. Immunolabeling of ubiquitin was variable, however, being more intense in AD than CBD samples. SDS-insoluble filaments were prepared from PHFs by boiling in the presence of SDS and 2-mercaptoethanol and collected by sedimentation. In both disorders, the pellets contained highly aggregated and bundled filaments, which were devoid of the amino but not the carboxyl terminal region of tau. Again, ubiquitin labeling was more intense in AD than CBD filaments. The present results suggest that ubiquitination has limited influence on SDS solubility, aggregation and bundling of PHFs; however, it may be one of the factors responsible for the ultrastructural variability and/or stability of filaments. Received: 6 March 1998 / Revised, accepted: 14 May 1998     

Coexistence of paired helical filaments and polyglucosan bodies in the same neuron in an autopsy case of Alzheimer’s disease

The coexistence of polyglucosan bodies (PBs) and paired helical filaments (PHFs) in the same neuron is reported in an autopsy case of Alzheimer’s disease. The patient was a 56-year-old Japanese male with a typical clinical course and pathological findings of Alzheimer’s disease. Electron microscopically, numerous neurofibrillary tangles, mainly composed of PHFs, were observed in the neuronal cytoplasm, axons and dendrites. Some of them coexisted with other filamentous structures, which comprised randomly oriented branching filaments with a diameter of 5–10 nm. These structures were compatible with PBs. Glial tangles could not be found. Coexistence of these two structures was thought to occur in neurites. Received: 16 October 1995 / Revised, accepted: 20 May 1996     

Paired pulse facilitation of GABAergic IPSCs in ventral horn neurons in neonatal rat spinal cord

Whole-cell patch-clamp recording of GABAergic inhibitory postsynaptic currents (IPSCs) were made in ventral horn neurons of neonatal rat lumbar spinal cord in slice. In contrast to the hippocampus where paired pulse depression is reported to be observed for GABAergic IPSCs, double pulse stimulation of GABAergic inputs resulted in enhancement in the amplitude of the second IPSC in the spinal ventral horn. The facilitation ratio was decreased during enhanced synaptic transmission by increasing Ca²⁺ concentration in the external recording solution. Baclofen and adenosine, which are reported to depress synaptic transmission by presynaptic mechanisms, depressed IPSCs and increased the facilitation ratio. A postsynaptic manipulation such as application of bicuculline or changing the driving force did not affect the facilitation ratio. These results suggest that paired pulse facilitation of GABAergic IPSCs observed in neonatal rat spinal ventral horn appears to be based upon a mechanism similar to that underlying frequency-dependent facilitation of excitatory synaptic transmission, and is sensitive to presynaptic changes in synaptic strength.     

Ultrastructural analysis of neurofibrillary tangles of Alzheimer's disease using computerized digital processing

Summary The ultrastructure of neurofibrillary tangles of Zlzheimer's disease was analyzed by computerized digital processing of electron micrographs. Processing of the electron micrographs consists of four steps: digitizing the electron micrograph, Fourier transformation, noise filtering and inverse Fourier transformation and Laplacian operation. In the present study, we have confirmed that neurofibrillary tangles are composed of a pair of helical filaments (PHF), which appear characteristically as an unbranched rigid structure. The periodicity of PHF is 78nm on the diffractogram. The dimensions of PHF obtained by our analysis, although basically similar to those described earlier by other investigators using conventional techniques, more precisely defines its structural conformation. We have also demonstrated that the spatial relationship of two filaments appears symmetrical after two-way tilting of the specimen about the axis of rotation. Our observations emphasize the importance of digital image processing as an effective tool for structural analytical research in biology and medicine.Supported in part by the Japanese Ministry of Culture (61570527) and the Research Committee on Senile Dementia of the Ministry of Welfare     

Effects of calcium and paired-pulse stimulation on hypoxia-induced hippocampal electrical changes

The influence of calcium concentration changes (2 and 4 mM) and of the paired-pulse stimulation (PPS) paradigm on the effects of hypoxia has been investigated in rat hippocampal slices. Because a high calcium concentration (4 mM) facilitates paired-pulse inhibition (PPI) at a 15-ms interpulse interval, the influence of hypoxia-induced effects were tested against calcium-induced PPI. In the PPS, unconditioned response at calcium concentrations of 2 and 4 mM, and 15- or 30-ms interpulse intervals of stimulation, no significant differences were found in the latency to induce a 50% amplitude decrease of the CA1 population spikes during hypoxia. On the contrary, in the conditioned response the latency to induce a 50% amplitude decrease of CA1 population spikes was significantly increased (p < 0.01) at 4 mM calcium, 15-ms interpulse interval with respect to experiments with 2 mM calcium, at 15- or 30-ms interpulse intervals. The data indicate that PPI is strongly affected during the early phases of hypoxia and also suggest that drugs increasing PPI could be successfully used for the treatment of brief anoxic or ischemic functional alterations.     

Hippocampal pyramidal cell response to 6-hydroxydopamine lesions of the rat ventral tegmental area

The occurence of neurofibrillary tangles (NFT) in the perforant pathway in association with dopaminergic cell loss in the ventral tegmental area (VTA) in human mesolimbic dementia, raises the possibility that denervation is a cause of NFT formation. This was tested in the rat by lesioning dopaminergic neurons which project to the hippocampus from the ventral tegmental area by means of stereotaxic injections of 6-hydroxydopamine. This resulted in the appearance of immunoreactivity to the paired helical filament protein plus an increase of tau and MAP-2 proteins in pyramidal neurons of CA-1 and CA-2. These neuronal responses to dopaminergic denervation are consistent with a precursor stage to NFT development.     

Lewy bodies are ubiquitinated

Summary The nature of Lewy bodies (LBs) in the brain stem and cerebral cortex in five cases of diffuse Lewy body disease and one case of Parkinson's disease with dementia were investigated immunocytochemically with various antibodies to cytoskeletal proteins, paired helical filaments (PHF) and ubiquitin. Antibodies to 200-kDa component of neurofilament, tau and PHF showed no significant reactions with most of LBs. Antibodies to high-molecular weight microtubule-associated proteins (HMWMAPs) moderately stained the periphery of a few of LBs. A monoclonal antibody to PHF (DF2) which recognizes ubiquitin, and polyclonal antibodies to ubiquitin immunostained virtually all of the typical and cortical LBs as intensely as Alzheimer's neurofibrillary tangles and senile plaque neurites: the periphery of LBs was darkly stained, whereas the central core of typical LBs and central zone of cortical LBs were less intensely stained or remained unstained. Immunoelectron microscopy of the LBs with DF2 revealed that immune reaction products were located on the filaments exclusively in the periphery of LBs, but not on those in the center. These findings suggest that both types of LBs are immunocytochemically indistinguishable despite some structural differences, and that peripherally located filaments in LBs are tagged with ubiquitin, an element required for the ATP-dependent proteolysis system in the cell. Antibodies to ubiquitin are the most useful marker of LBs ever known.Supported in part by grants-in-aid from the Ministry of Education, Science and Culture, Japan     

Phases in the development of a penicillin epileptiform focus in rat neocortex

Somatosensory evoked potentials and potentials evoked by direct cortical stimulation were recorded from layer IV of the somatosensory area of the cerebral cortex in urethane anaesthetised rats. Penicillin was expelled electrophoretically from the tip of a drug-filled micropipette at constant rates into layer IV. Small fluxes of penicillin (with electrophoretic currents of -50 to -90 nA) resulted in the appearance, after a delay of 1–2 min, of an enhancement of amplitude in the voltage of both types of evoked potential, unaccompanied by any prolongation of the waveform or spontaneous focal epileptiform discharges. The amplitude of the enhanced evoked potential exhibited a strength-response curve which was a scaled-up version of the curve before penicillin, the scaling factor reflecting the enhancement of amplitude. As the interval between a pair of stimuli was increased, the magnitude of the response to the second stimulus recovered, following a time course similar to that before penicillin. With larger fluxes of penicillin (with electrophoretic currents of -250 to -1000 nA) the amplitude of evoked potentials rose more rapidly and to a higher level; as the concentration of penicillin rose, this enhancement of amplitude led into a second phase, in which there was additionally an increase in the duration of the evoked potentials and the appearance of spontaneous epileptiform discharges. The evoked potentials in this situation showed physiological properties different from those before penicillin application. The strength-response curve exhibited a discontinuity, indicating the evoked potential to be the sum of a physiological response and an epileptiform discharge, the former being graded with stimulus strength and the latter being all or none. With paired stimuli, the response to the test stimulus was profoundly depressed for long conditioning-test intervals by comparison with the relatively rapid recovery exhibited by normal brain. When a cuboid of cortex measuring 0.6 mm² or less was partially isolated subpially by incisions extending through the upper half of the cortical mantle, all the features of hyperexcitability produced by penicillin in intact cortex were blocked. This shows that even the simple enhancement of evoked potentials, which is the earliest indicator of hypersynchronous activity, differs from an exaggeration of normal evoked activity in requiring a larger community of neurones with their horizontal intracortical connections intact.