Biomedical subjects

Sheng He

Publications and source records attributed to Sheng He.

51 records · Page 3Linked to original sources

PubMed2004

Behavioral and functional MRI study of attention shift in human verbal working memory.

The tripartite model of memory proposed the requirement of attentional switching when accessing different items in working memory [J. Exp. Psychol. Learn. Mem. Cogn. 27 (2001) 817]. This internal focus of attention is limited to just one item and the switching process is time-consuming [Mem. Cogn. 26 (1998) 263]. In the current study, given a three-digit list stored in working memory, we found that it took longer to shift attention in the direction of "Upstream" than "Downstream", and that each shift was a "single step" process. To investigate the neural basis of this type of attention switching, we performed a functional MRI study. The results revealed that at least three important brain areas are involved, including the left dorsal lateral prefrontal cortex, the cingulate gyrus, and the medial occipital cortex. These areas all showed greater activation in the attention shift condition compared to control conditions of no (or decreased) attention shift requirements. In addition, the hemodynamic activities in these areas are highly correlated, suggesting a strong functional connectivity between them. Taken together with evidence from several recent investigations, our results suggest that these areas each play an important and specific role in collaboratively supporting the function of attention shift in working memory.

Adolescent↗

PubMed2004

131I-recombinant human EGF has antitumor effects against MCF-7 human breast cancer xenografts with low levels of EGFR.

This study investigated the inhibitory action of (131)I-recombinant human EGF ((131)I-rhEGF) on MCF-7 human breast cancer tumor development in nude mice. The activity and tumor uptake of (131)I-rhEGF was measured by tissue distribution assay, and its effect on tumor growth was measured by monitoring tumor size after treatment with (131)I-rhEGF. Changes in tumor cell ultrastructure were observed by transmission electron microscopy (TEM), and pathological changes in tumor tissue were observed by light microscopy. The tissue distribution assay revealed that (131)I-rhEGF was markedly absorbed by the tumor and reached its maximal uptake rate (16.73%ID. g(-1)) at 120 hours at which point the drug concentration in the tumor was 11.1-fold, 8.1-fold, and 6.6-fold higher than that in blood, liver, and kidneys, respectively. Tumor size measurements showed that tumor development was significantly inhibited by intravenously and intratumorally injected (131)I-rhEGF. Tumor inhibition rates (82.0% and 80.7%, respectively) were significantly higher than those of tumors treated with (131)I (7.49%) and (131)I-HSA (6.91%; P < 0.05). TEM and light microscopy revealed that intravenous and intratumoral injection of (131)I-rhEGF could significantly damage and ultimately kill tumor cells. Our results suggest that (131)I-rhEGF suppresses development of xenografted breast cancer cells in nude mice, providing a novel candidate for receptor-mediated targeted radiotherapy.

Animals↗

PubMed2004

[Experimental study on the activity of Staphyloccocal enterotoxin A liposome for inducing cytotoxicity of TIL from human hepatocellular carcinoma against tumor cells].

OBJECTIVE: To investigate the activity of Staphyloccocal enterotoxin A liposome (L-SEA) for inducing cytotoxicity of tumor infiltrating lymphocytes (TIL) against tumor cells. METHODS: TIL were isolated from the tumor tissues of five hepatocellular carcinoma patients. L-SEA, SEA and IL-2 were tested in vitro for their activity levels in stimulating TIL proliferation. The TNF-alpha and IFN-gamma secretion and cytotoxicity of TIL against HepG-2 liver cancer cells were estimated by ELISA and MTT, respectively. RESULTS: Both L-SEA and SEA significantly stimulated the proliferation of TIL. The cytokine secretion of L-SEA group was significantly higher than that of IL-2 group (P < 0.05). There was no significantly statistical difference in cytokine secretion between L-SEA group and SEA group (P > 0.05) except that IFN-gamma secretion of L-SEA group was lower than that of SEA group at day 4 (P < 0.05). Both L-SEA and SEA had potent ability to induce TIL cytotoxicity against HepG-2 cells. And no significant difference was observed between these two groups (P > 0.05). CONCLUSION: These results suggest that L-SEA is as efficient as SEA in activating TIL.

Adult↗

PubMed2004

[Experimental research into the inhibitory effect of 131I-recombinant human epidermal growth factor on the growth of breast cancer in vivo].

This experiment was designed to study the effect of 131I-recombinant human epidermal growth factor (131I-rhEGF) on the growth of tumor in nude mice loaded with human breast cancer. Bioactivity of 131I-rhEGF and uptake of 131I-rhEGF in breast cancer tissue were verified using biodistribution experiment of 131I-rhEGF in the nude mice loaded with human breast cancer. The effect of 131I-rhEGF on the growth of tumor was assessed via the growth experiment of tumor in the nude mice loaded with human breast cancer. The ultrastructural change of the tumor cell treated with 131I-rhEGF was observed under transmission electron microscope, and the pathological change of the tumor tissue treated with 131I-rhEGF was detected by biopsy. The results showed that the tumor tissue of nude mice bearing human breast cancer obviously takes in 131I-rhEGF; that intravenous administration and intratumoral administration of 131I-rhEGF both obviously inhibit the growth of tumor, the inhibition rates (82.00% and 80.70%) being remarkably higher than that of 131I (7.49%) and that of 131I-HSA (6.91%) (P<0.05); and that intravenous and intratumoral administration of 131I-rhEGF both obviously damage and kill tumor cells. Therefore, 131I-rhEGF can inhibit the growth of human breast cancer cell in nude mice; it is a potential receptor-mediated radioactivity targeting drug for treating breast cancer.

Animals↗

PubMed2003

[Transplantation of fetal cardiomyocyte regenerates infarcted myocardium in rats].

OBJECTIVE: To investigate the feasibility and efficiency of fetal cardiomyocyte transplantation into the rat model of myocardial infarction. METHODS: Cardiomyocytes were isolated from aborted human embryos aged 12 - 16 weeks and cultured for 5 days to confirm their viability. Rat model of extensive myocardial infarction (MI) was established in 18 male Wistar rats by ligating the descending anterior branch of left coronary artery and the 18 rats were randomly divided into 2 groups: transplantation group (n = 7, 2 x 10(6) fetal cardiomyocytes were transplanted into the myocardial scar) and culture medium injection group (n = 6, culture medium was injected into the myocardial scar) 5 days after extensive MI was caused. Another 6 rats undergoing sham operation were used as controls. Echocardiography was performed before and 60 +/- 3 days after the implantation to assess the left ventricular (LV) remodeling and cardiac function. Then the rats were killed and their heart were harvested to undergo HE staining, immunohistochemical examination with antibody against human alpha-actin smooth muscle (SMA) isoform, and light microscopy. RESULTS: Light microscopy revealed the presence of engrafted human fetal cardiomyocytes in the infarcted myocardium and the presence of nascent intercalated disks connecting the engrafted fetal cardiomyocytes and the host myocardium. The engrafted fetal cardiomyocytes were SMA positive. Serial echocardiography revealed that cell transplantation prevented scar thinning, LV further dilatation and dysfunction while the control animals developed scar thinning, significant LV dilatation accompanied by progressive deterioration in LV contractility. CONCLUSION: Fetal cardiomyocytes can be implanted and survive in the infarcted myocardial cells, thus preventing the scar thinning, and LV further dilatation and dysfunction.

Animals↗

PubMed2003

Patterns of activity in the categorical representations of objects.

Object perception has been a subject of extensive fMRI studies in recent years. Yet the nature of the cortical representation of objects in the human brain remains controversial. Analyses of fMRI data have traditionally focused on the activation of individual voxels associated with presentation of various stimuli. The current analysis approaches functional imaging data as collective information about the stimulus. Linking activity in the brain to a stimulus is treated as a pattern-classification problem. Linear discriminant analysis was used to reanalyze a set of data originally published by Ishai et al. (2000), available from the fMRIDC (accession no. 2-2000-1113D). Results of the new analysis reveal that patterns of activity that distinguish one category of objects from other categories are largely independent of one another, both in terms of the activity and spatial overlap. The information used to detect objects from phase-scrambled control stimuli is not essential in distinguishing one object category from another. Furthermore, performing an object-matching task during the scan significantly improved the ability to predict objects from controls, but had minimal effect on object classification, suggesting that the task-based attentional benefit was non-specific to object categories.

Brain Mapping↗

PubMed2003

Temporal characteristics of binocular rivalry: visual field asymmetries.

Very little is known about the mechanisms that drive the alternation between the two views during binocular rivalry. A key property of the rivalry process is the rate at which the two views alternate. Understanding the factors that affect the rate of the alternation is critical to the final understanding of the underlying process. Using a circular and a radial grating as the rivalry stimuli, we observed a significantly faster binocular rivalry when stimuli were presented in the right visual field than that in the left visual field for the right-handed observers, and a reversed asymmetry for the left-handed observers. In both groups, rivalry was faster for stimuli presented in the lower visual field than that in the upper visual field. This pattern of results suggests that (1) rivalry is likely a locally driven process and (2) the visual brain in the left hemisphere may be the faster one of the two hemispheres in right-handed people.

Adaptation, Ocular↗

PubMed2003

A functional MRI study of high-level cognition. II. The game of GO.

GO is a board game thought to be different from chess in many aspects, most significantly in that GO emphasizes global strategy more than local battle, a property very difficult for computer programs to emulate. To investigate the neural basis of GO, functional magnetic resonance imaging (fMRI) was used to measure brain activities of subjects engaged in playing GO. Enhanced activations were observed in many cortical areas, such as dorsal prefrontal, parietal, occipital, posterior temporal, and primary somatosensory and motor areas. Quantitative analysis indicated a modest degree of stronger activation in right parietal area than in left. This type of right hemisphere lateralization differs from the modest left hemisphere lateralization observed during chess playing.

Brain Mapping↗

PubMed2003

A functional MRI study of high-level cognition. I. The game of chess.

Chess is a game that involves many aspects of high level cognition and requires sophisticated problem solving skills. However, there is little understanding of the neural basis of chess cognition. This study employed functional magnetic resonance imaging (fMRI) to identify cortical areas that are active during the analysis of chess positions compared with a spatial task with matched visual stimuli. Bilateral activation was revealed in the superior frontal lobes, the parietal lobes, and occipital lobes. Some small areas of activation were observed unilaterally in the left hemisphere. The left hemisphere showed more activation than the right. Results are discussed in relation to a similar brain imaging study on the game Go.

Adult↗

PubMed2003

Functional comparison of primacy, middle and recency retrieval in human auditory short-term memory: an event-related fMRI study.

Primacy and recency effects refer to the better performance or shorter response time on the first and last items than the middle ones of a memory list. In order to investigate its neural basis in auditory short-term memory, event-related fMRI was used to measure brain activities when subject was recalling the first, the last, or the middle items. Recalling the middle item was associated with more extensive activation in the left parietal and visual cortex, basal ganglia, and dorsal cerebellum. Recalling items from different serial positions also resulted in different activation time courses in the bilateral primary auditory cortex, left prefrontal cortex and left premotor cortex. These data indicate that the auditory cortex may serve as a transient storage or the auditory input buffer, which seems to play an important role in the primacy and recency effects.

Acoustic Stimulation↗

PubMed2003

[Application of virtual reality modeling language in the fields of medical digital image].

This research aims at the process of three-dimensional(3D) reconstruction from medical body data using VRML and VC++, JavaScript language and focuses on the application of VRML for 3D reconstruction of medical digital images. The 2D medical digital images firstly are modified in VC++ language. Then, the images are manipulated by mould built in VRML and modified in JavaScript language. Finally, the 3D reconstruction of body internal organs can be formed in high quality near to those got in traditional methods. Furthermore, VRML browser can offer better windows of man-computer interaction in real time environment. As a new method and tool quite different from traditional ways of 3D reconstruction, VRML is useful for the visualization of medical 3D reconstruction based on 2D images and has a promising prospect in the field of medical image.

Image Processing, Computer-Assisted↗

PubMed2003

[Effects of quercetin on the proliferation and apoptosis in transplantation tumor of breast cancer in nude mice].

OBJECTIVE: To investigate the effects of quercetin on tumour growth, cell proliferation and apoptosis in transplantation tumor of breast cancer cell line MCF-7 in nude mice. METHODS: MCF-7 cells were inoculated into the mammary fatty pad of nude mice to establish breast cancer model, then twenty-four BALB/c nude mice with xenograft tumor were randomized into four groups: Control group, Quercetin group, 5-Fu group and Quercetin + 5-Fu group. After 15 days treatment, samples of tumor were collected. The sections of tumor were observed under light microscope and electron microscope. Cell apoptosis in situ was examined by a Tunel assay, and the expressions of ki67 antigen and B-cell lymphoma/leukemia-2 (Bcl-2) were detected by immunohistochemistry. RESULTS: 1. The tumor weight of Control group was significantly higher than those of Quercetin group, 5-Fu group and Quercetin + 5-Fu group (P < 0.05). 2. Immunohistochemical staining of ki67 showed that the ki67 label index (ki67-LI) displayed significant difference between Control group and Quercetin group, 5-Fu group, Quercetin + 5-Fu group, and so did the staining of Bcl-2. 3. Detection of apoptosis in situ showed that apoptosis index (AI) was significantly higher in Quercetin group, 5-Fu group and Quercetin + 5-Fu group than in control group (P < 0.01), and higher AI was observed in Quercetin + 5-Fu group as compared with the AI in Quercetin group and 5-Fu group (P < 0.05). CONCLUSION: Quercetin can inhibit the growth of transplantation tumor of breast cancer cell line MCF-7 in nude mice.

Animals↗

PubMed2003

[An experimental study of gastric pacing on postsurgical gastric dynamic dysfunction].

OBJECTIVE: To probe the feasibility and curative effect of gastric pacing on postsurgical gastric dynamic dysfunction. METHODS: Thirty-two rabbits were divided into four groups. The gastric dynamic indices of applying gastric pacing to the experimental animal model of acute post-vagotomy gastroparesis were compared with those of the groups treated with erythromycin (1 mg/kg). RESULTS: The measurements of "gastroduodenal pressure at different sites" of the gastric pacing group and erythromycin group were higher than those of the before pacing group respectively (P < 0.001). The gastric pressure of the gastric pacing group was higher than that of the erythromycin group (P < 0.001). No significant difference in the duodenal pressure was observed between the above two groups (P > 0.05). The measurements of pressure at different sites (gastric fundus; gastric corpus; gastric antrum) after stopping pacing were higher than those of the erythromycin group, respectively (P < 0.01, P < 0.05, P < 0.05). The "pressure gradient between gastric antrum and duodenum" of the gastric pacing group was higher than that of the erythromycin group (P < 0.01). The gastric emptying rate of the gastric pacing group (64.41% +/- 6.66%) was significantly higher than that of the erythromycin group (53.73% +/- 7.09%) (P < 0.01). CONCLUSION: Applying higher frequency gastric pacing can markedly enhance the gastric pressure, the pressure gradient between gastric antrum and duodenum, and the gastric emptying rate.

Animals↗

PubMed2003

[Quantitative pathologic technique in prognostic identification of breast carcinoma with negative lymph node].

OBJECTIVE: To study the prognostic identification of lymph node negative breast carcinoma by quantitative pathologic technique. METHODS: Several morphometrical parameters, DNA content of cell nuclei were detected by means of a quantitative pathologic technique on 102 patients with lymph node negative invasive breast duct carcinoma. The effects of potential prognostic factors of lymph node negative breast cancer patients were assessed by Cox's proportional hazards regression model. RESULTS: DNA index, minimal diameter of nuclei, area of nuclei, maximal diameter of nuclei, and the perimeter of nuclei are important factors to influence the prognosis. CONCLUSION: Quantitative pathologic technique combined with valid statistical methods, as an objective means of assessing prognosis, may reliably improve the outcome in lymph node negative breast cancer.

Adult↗

PubMed2002

[Study on preparation and tissue distribution of SEA liposomes].

OBJECTIVE: To make a study on the preparation and tissue distribution of staphylococcal enterotoxin A (SEA) liposomes and to provide scientific basis for the therapy of liver cancer by using SEA liposomes. METHODS: SEA liposomes were prepared by reverse-phase evaporation; the diameter and entrapment efficiency (EC) of SEA liposomes were determined. 125I labeled SEA solution and 125I-SEA liposomes were administrated intravenously to mice, respectively. The radioactivity of the organs was determined by gamma-counter. RESULTS: The mean diameter and EC of SEA liposomes were 505 +/- 34 nm and 44.1% +/- 4.8%, respectively. SEA liposomes were found mainly distributed in the liver and spleen. SEA liposomes had a higher blood clearance, compared with SEA solution; SEA solution had high-radio-activity in plasma and kidney; there was statistical significance between the two groups (P < 0.05). CONCLUSION: The preparation method of SEA liposomes is simple and repeatable. SEA liposomes possess liver-targeting properties and may provide a new application foreground for the treatment of liver cancer.

Animals↗