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S T Xu

Publications and source records attributed to S T Xu.

At least 19 recordsLinked to original sources
PubMed2004

The relationship between solitary pulmonary nodules and bronchi: multi-slice CT-pathological correlation.

AIM: To investigate the relationship between solitary pulmonary nodules (SPN) and bronchi and its value in predicting the nature of the SPN. MATERIALS AND METHODS: We performed volumetric targeted scans of 0.5 mm collimation with multi-slice computed tomography (MSCT), reconstructing multiplanar reconstructions (MPR), curved multiplanar reconstructions (CMPR) and surface-shaded display (SSD) images of bronchi in 78 consecutive patients with SPN (53 malignant and 25 benign) and correlated the findings with those of macroscopic and microscopic specimens. RESULTS: With this CT protocol, the third to seventh-order bronchi were shown continuously and very clearly in all patients. CT findings were consistent with those of specimens. CT demonstrated the relationship between the SPN and bronchi in 46 (86.8%) malignant and 18 (75.0%) benign nodules. Five types of tumour-bronchus relationships were identified with MSCT. Type I: the bronchus was obstructed abruptly by the SPN; type II: the bronchus penetrated into the SPN with tapered narrowing and interruption; type III: the bronchial lumen shown within the SPN was patent and intact; type IV: the bronchus ran around the periphery of the SPN with intact lumen; type V: the bronchus was displaced, compressed and narrowed by the SPN. Malignant nodules were most commonly of type I (58.5%), secondly of type IV (26.4%) and rarely of type V (1.9%). Benign nodules were most often of type V (36.0%), followed by type III (20.0%), type I (16.0%), and there were no type II. Types I, II and IV were more common in malignant nodules, whereas type V was seen more frequently seen in benign nodules (p<0.05). There was no statistically significant difference between the two groups regarding type III. CONCLUSION: Ultra-thin section with MSCT and MPR, CMPR and SSD reconstruction can improve the demonstration of the patterns of tumour-bronchus relationships, which can reflect the pathological changes of the nodules to some extent and help differentiate malignant from benign tumours.

Aged↗
PubMed1996

[Changes of synaptic transmission efficiency in the MF-CA3 and PP-CA3 pathways of rat hippocampus during discrimination learning].

Electrophysiological and behavioral studies were performed in rat to investigate the changes of synaptic efficacy of the two inputs of hippocampal CA3 area [Mossy Fiber (MF) -CA3 and Perforant Path (PP) -CA3] during discrimination learning. The results showed that: (1) Amplitude of the population spike (PS) of both from MF-CA3 and PP-CA3 increased simultaneously with the establishment of conditioned response (CR) and both reached their maxima before CR reached the criterion of acquisition. (2) During natural extinction of CR, the amplitude of PS of both inputs decreased also simultaneously to their per-training level. These results indicated that the learning-dependent long-term potentiation (LTP) in both MF-CA3 and PP-CA3 inputs developed and extinguished synchronously, suggesting that the changes of synaptic efficacy of different inputs of hippocampal CA3 area coordinated during discrimination learning.

Animals↗
PubMed1993

[The histological change, MRI manifestation and neurological deficiency of old spinal cord injury].

The L1 spinal cord of 22 dogs were injured by modified Allen's method. During the interval of 50-100 days after injury, MR imaging were performed and the specimens of the injured spinal cord were taken out immediately for histological examination. T1 weighted images were used to observe changes of spinal cord signals. In 7 cases with cavity formation in the central part of the injured spinal cord was found histologically, there was small cavity in the spinal cord signal on MRI. In 12 cases with necrosis and softening in central area of the spinal cord, the T1 weighted image showed hypointensity in central part of spinal cord signal, and in 3 cases with necrosis, degeneration and glial replacement histologically, the MR image showed unhomogeneous and slight hyointensity signal. These entities suggested that the MRI appearances of spinal cord injury represented the histological changes of the spinal cord. Clinically, the MRI manifestation of 76 cases of old spinal cord injury were closely related to their neurologic deficiency. Cases of transection signal of spinal cord were excluded. There were six types of MRI appearances. In 40 cases of complete paraplegia, the MRI appearances were enlarged hypointensity signal in 16 hypointensity signal in 4, atrophy of the spinal cord in 13, large cavity in 3 and unhomogeneous with compression in 1. After treatment, there were no recovery in all cases. 36 cases of incomplete paraplegia their MRI showed normal signal but compressed in 16, all had good recovery after treatment. Unhomogenous signal with slight hypointensity was found in 11, they one frankle degree recovery after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Effects of 6-OHDA lesions of the bilateral dorsal noradrenergic bundle on learning-dependent long-term synaptic potentiation in dentate gyrus].

In the present study, the role of NE in learning-dependent long-term potentiation (LdLTP) was investigated by examining the effects of 6-hydroxydopamine (6-OHDA) lesion made in the bilateral dorsal noradrenergic bundle on the changes of synaptic efficacy in dentate gyrus (DG) and related conditioned response during drinking conditioning. Bilateral injection of 6-OHDA (12 micrograms/4 microliters) into the dorsal noradrenergic bundle caused a continuous decrease of the amplitude of population spike (PS) reaching a value of 50 +/- 6.3% and 28 +/- 6.4% respectively at the 6th and the 12th day after injection of the drug. During this period of 7 days, the LdLTP could not be produced in spite of 20 trainings per day for a total of 140 trials, and the conditioned drinking response could not be established. The above results indicate that normal levels of norepinephrine in the hippocampus are necessary to the establishment of LdLTP in the DG and suggest that the development of LdLTP in the DG may be modulated by the nucleus locus ceruleus via the dorsal noradrenergic bundle.

Animals↗
PubMed1993

[Studies on the mechanism of the protective immunity against Schistosoma japonicum--cellular immune responses].

Kinetics of cellular immune responses was studied in C57BL/6 mice immunized with irradiation-attenuated vaccine, cryopreserved and irradiated vaccine or frozen-thawn vaccine. The results and analysis of correlation between cellular responses and resistance showed that cellular immune responses played an important role in the protective immunity against Schistosoma japonicum.

Animals↗
PubMed1992

[Role of N-methyl-D-aspartate receptor in the maintenance of learning-dependent long-term potentiation in rat hippocampal CA3 area].

The effect of microinjection of 2-amino-5-phosphonovaleric acid (APV), a selective NMDA receptor antagonist, into the rat hippocampal CA3 area on the synaptic efficacy and related conditioned behavior during the acquisition and consolidation of discrimination learning behavior was examined. The results showed: (1) After population spike (PS) amplitude had just increased to the maximum through training i.e. learning-dependent LTP had just formed, APV 1 microliter (2 mmol/L) was injected into CA3 area, then the rats were trained during the time of efficacy of the drug in every experimental block. The result demonstrated that the PS amplitude could not be maintained at the highest level but decreased to the pre-experiment level after 8 blocks. Correct response percentage of rats could not be consolidated with further training but decreased to less than 10%. (2) After the PS amplitude had kept up at the highest level, APV 1 microliter (2 mmol/L) was injected into CA3 area, then the rats were trained during the time of efficacy of the drug in every experimental block, in which case the PS amplitude also could not be maintained at the highest level but decreased to the pre-experiment level after 14 blocks. Correlatively, when the correct response percentage of rats decreased gradually to less than 10%, the conditioned response of the animals extinguished, but its extinction speed was slower than it was in result (1). These results suggest that the NMDA receptor in CA3 area plays an important role in the maintenance of the learning-dependent long-term potentiation.

2-Amino-5-phosphonovalerate↗
PubMed1992

[Percalcar Steinmann's pins fixation of intratrochaner fixation fracture. Clinical observation].

80 cases of intratrochaner fractures were treated by fixation of 4 Steinmann's pins which were 3.5 mm in diameter and inserted percutaneously through the calcar and compression trabeculae and distension trabeculae respectively. They were compared with the cases treated by skeletal traction or fixed by Nail-plate or angle plate. The rate of bony union in fixed position in the percalcar Steinmann's pins group was 83.7%. Normal neck-shaft angle accounted to 53.1% in the traction group. Varus deformity occurred in 16.3% cases of the Steinmann's pins group, and 35.9% cases of the traction group. The deformity was most frequently seen in cases of type IIIa and IV. No fixation failure occurred in the Steinmann's pins group. The Steinmann's pins passing through the outer cortex, calcar and compression trabeculae produced strong fixation and it's direction was in parallel to the weight-bearing line of the hip, with less shearing force and much compression force distributed on the fracture line. The operation was done under local anesthesia. No blood transfusion and early mobilization were the advantages of this method.

Aged↗
PubMed1991

[Internal fixation for intertrochanteric fracture. Biomechanical study].

A Type IIIa intertrochanteric fracture was made on the preserved femurs of adult cadavers. The fracture was fixed by 4 methods: Percalcar Steinmann's pins, Knowle's pins, Nail plate and Angle plate. The loading limit of the fixations were 150, 140, 70 and 40 kg respectively. In fatigue test the loading ability of the percalcar Steinmann's pins were 4 times greater than that of Nail plate or Angle plate. In Nail plate and Angle plate. The pathological section of the upper femur showed the most bony destruction was at the trabecula beneath the lateral cortex, and in the percalcar Steinmann's, it was at the neck trabecula, where the cal car plays an important role in supporting the loading of the lowest pin. It was found that the level arm was shortened and the loading ability increased. As the direction of the lowest pin was nearly parallel to the loading axis of the hip. The calcar suffered less shearing force. These findings showed that the percalcar Steinmann's pins fixation is the best in these 4 methods.

Biomechanical Phenomena↗
PubMed1991

[Diagnostic value of magnetic resonance imaging for chronic injury of spine and spinal cord].

From March 1989 to July 1990, Magnetic resonance imaging (MRI) examination was conducted in 60 patients with chronic injuries of the spine and the spinal cord, of whom 32 patients received exploration and decompression operation. Based on the results of MRI, clinical neurological examinations, biological electrical examinations were compared treatment. MRI proved to show the minute changes of the spine, the definite location of spinal compression, the narrowing of spinal canal and the actual cause of compression objects. Thus, it is helpful in selecting treatment and in predicting prognosis.

Humans↗
PubMed1990

[Effect of scopolamine and picrotoxin on the learning-dependent long-term synaptic potentiation].

The purpose of this study was to investigate the effects of microinjection of scopolamine, a M-cholinergic antagonist and picrotoxin, a GABA-ergic antagonist into the rat hippocampal CA3 area on the learning-dependent long-term potentiation (LDLTP) during the establishment, extinction and re-establishment of conditioned drinking response. Following stimulation of the perforant path, field potentials of hippocampal CA3 of freely moving rats were recorded. The results were as follows: the synaptic efficacy and the development of LDLTP in hippocampal CA3 were depressed significantly by scopolamine, but the extinction of LDLTP was accelerated. Picrotoxin significantly enhanced synaptic efficacy and facilitated the development of LDLTP, but it depressed the extinction of LDLTP. Meanwhile, the establishment or extinction of drinking conditioning was correspondingly depressed or accelerated. Moreover, the development of LDLTP and its extinction preceded the development and extinction of drinking conditioning. The results provide further evidence indicating that LDLTP might be one of the neuronal mechanisms underlying behavioral learning and memory. Moreover, it seems that M-cholinergic receptors and GABA-ergic receptors in rat hippocampal CA3 area are involved in the development and retention of LDLTP.

Animals↗
PubMed1990

[Effect of electroshock on learning-dependent long-term potentiation in rat hippocampal CA3 area].

Population spikes were recorded from hippocampal CA3 of freely moving rats following stimulation of the perforant path. Six rats were trained to perform conditioned drinking behavior. (1) Animals were treated with electroshock in less than 15 minutes after daily training session for a period of 6 consecutive days. Synaptic efficacy did not increase and the conditioned response could not be established during the behavioral training in four rats, synaptic efficacy was increased, the long-term potentiation (LTP) appeared and the conditioned behavior was established in other two rats. (2) After consolidation of conditioned behavior, electroshock temporarily caused suppression of the learning-dependent LTP and the correlative conditioned response. Both LTP and the correlative conditioned response recovered in one to four hours after electroshock. In these cases, the maximal development of LTP preceded the development of conditioned behavior. The results indicated that the learning-dependent LTP might be one of the neural substrates underlying learning and memory.

Animals↗
PubMed1989

[Vertebrectomy in treating fracture-dislocation of the spine with paraplegia].

From April 1980 to August 1984, 11 cases of fracture--dislocation of spine at the level of T-11 to L-2 with obvious kyphosis at the site of displacement, with paraplegia, were treated by vertebrectomy through posterior median approach. The operations were performed 2 to 28 weeks, averaging 8 weeks, after injury. 5 of the 9 patients who had complete paraplegia suffered also causalgia in both legs. The other 2 had incomplete paraplegia only. Follow-up study, 4 years and 5 months post-operation on average, revealed complete reduction of the fracture-dislocation in 10 patients and incomplete in one, getting solid bony union in all. Concerning the neurological findings of the 9 complete paraplegic patients, 5, who had suffered from causalgia got varying degree of relief, 5 regained sensation of pain in region 2 segments lower, of the 2 incomplete paraplegic patients, 1 regained sensation of pain in both legs and muscular power of degree 4 in both thighs, so that walking became possible, while the another one fell into complete paraplegia, because of compression of the cord at T-10 happened during operation and showed no signs of recovery afterward.

Adult↗
PubMed1989

[The learning dependent long-term synaptic potentiation in the rat hippocampal CA3 region].

The purpose of this study is to investigate the changes of synaptic efficacy in the rat hippocampal CA3 region during establishment, extinction and re-establishment of conditioned drink response by means of implanted electrodes and behavioral observation. The monosynaptic population excitatory postsynaptic potential (EPSPs) and population spike (PS) elicited by stimulating the perforant path were recorded. The results showed that the long-term potentiation (LTP) in the hippocampal CA3 region appeared with the establishment of conditioned response, the LTP extinguished with experimental extinction of conditioned response and reappeared during the re-establishment of conditioned response. Moreover, both maximal level of LTP and its complete extinction preceded those of conditioned behavior, suggesting that the LTP was learning-dependent. In addition, the enhanced PS was not presented immediately after behavioral training, and developed within subsequent 24 h, with a maximum at the 4th hour. The magnitude of conditioned response depended on the level of LTP. A cross-correlation analysis of the slopes of PS and EPSPs indicated that the changes of PS were caused by alterations of synaptic transmission. These results suggest that the learning-dependent LTP might be one of the neuronal substrates underlying behavioral learning and memory.

Action Potentials↗