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Y Pu

Publications and source records attributed to Y Pu.

At least 37 records · Page 2Linked to original sources
PubMed2000

Brain activation in the processing of Chinese characters and words: a functional MRI study.

Functional magnetic resonance imaging was used to identify the neural correlates of Chinese character and word reading. The Chinese stimuli were presented visually, one at a time. Subjects covertly generated a word that was semantically related to each stimulus. Three sorts of Chinese items were used: single characters having precise meanings, single characters having vague meanings, and two-character Chinese words. The results indicated that reading Chinese is characterized by extensive activity of the neural systems, with strong left lateralization of frontal (BAs 9 and 47) and temporal (BA 37) cortices and right lateralization of visual systems (BAs 17-19), parietal lobe (BA 3), and cerebellum. The location of peak activation in the left frontal regions coincided nearly completely both for vague- and precise-meaning characters as well as for two-character words, without dissociation in laterality patterns. In addition, left frontal activations were modulated by the ease of semantic retrieval. The present results constitute a challenge to the deeply ingrained belief that activations in reading single characters are right lateralized, whereas activations in reading two-character words are left lateralized.

Adult↗
PubMed2000

Demonstration of the medullary lamellae of the human red nucleus with high-resolution gradient-echo MR imaging.

BACKGROUND AND PURPOSE: The human red nucleus is not a uniform structure. It is composed of caudally located magnocellular and rostrally located parvicellular subnuclei. In fact, the latter forms the bulk of the human red nucleus and can be subdivided histologically by two medullary lamellae into three parts. Because iron is deposited in the human red nucleus and gradient-echo sequences are more sensitive than spin-echo sequences in the detection of iron, a high-resolution gradient-echo MR sequence was used in this study to determine whether the medullary lamellae of the normal human red nucleus could be detected in vivo. METHODS: Ten healthy volunteers (seven men and three women, 27-48 years old) were examined with a high-resolution T2-weighted gradient-echo MR sequence using a 1.9-T MR imager. The scanning parameters were 60/40/15 (TR/TE/excitations) with a flip angle of 20 degrees , a pixel size of 1 x 1 mm, and a slice thickness of 5 mm. RESULTS: The medullary lamellae were depicted in all subjects in three imaging planes: coronal, oblique axial, and oblique sagittal. The signal intensity of the lamellae was consistently higher than that of other parts of the red nucleus on all images. With the lamellae, the parvicellular subnucleus of the human red nucleus can be divided into its subdivisions. CONCLUSION: High-resolution gradient-echo MR imaging is capable of depicting the medullary lamellae of the normal human red nucleus in vivo.

Adult↗
PubMed1999

Temporal dissociation of parallel processing in the human subcortical outputs.

Many tasks require rapid and fine-tuned adjustment of motor performance based on incoming sensory information. This process of sensorimotor adaptation engages two parallel subcorticocortical neural circuits, involving the cerebellum and basal ganglia, respectively. How these distributed circuits are functionally coordinated has not been shown in humans. The cerebellum and basal ganglia show very similar convergence of input-output organization, which presents an ideal neuroimaging model for the study of parallel processing at a systems level. Here we used functional magnetic resonance imaging to measure the temporal coherence of brain activity during a tactile discrimination task. We found that, whereas the prefrontal cortex maintained a high level of activation, output activities in the cerebellum and basal ganglia showed different phasic patterns. Moreover, cerebellar activity significantly correlated with the activity of the supplementary motor area but not with that of the primary motor cortex; in contrast, basal ganglia activity was more strongly associated with the activity of the primary motor cortex than with that of the supplementary motor area. These results demonstrate temporally partitioned activity in the cerebellum and basal ganglia, implicating functional independence in the parallel subcortical outputs. This further supports the idea of task-related dynamic reconfiguration of large-scale neural networks.

Basal Ganglia↗
PubMed1999

Quantification of dynamic changes in cerebral venous oxygenation with MR phase imaging at 1.9 T.

A double-echo magnetic resonance (MR) phase imaging method was used to measure the time-dependent changes in regional cerebral venous blood oxygenation during neural stimulation. Our results showed that a finger opposition task induced an absolute increase of blood oxygenation level of deltaY = 0.16+/-0.05 (n = 6), which was measured in the small veins located in the left central sulcus. It was observed that there is a long temporal delay of approximately 27 sec after the onset of the task to reach the steady-state venous oxygenation. This work demonstrated that MRI is a powerful clinical tool for in vivo monitoring of the dynamic nature of organ-specific venous blood oxygenation.

Adult↗
PubMed1999

Cerebral blood flow measurement by dynamic contrast MRI using singular value decomposition with an adaptive threshold.

Singular value decomposition (SVD) is a promising deconvolution technique for use in dynamic contrast agent magnetic resonance perfusion imaging. Computer simulations, however, show that the selection of the threshold for SVD affects the accuracy of the cerebral blood flow measurements and may distort the shape of the vascular residue function. In this report, a pixel-by-pixel thresholding method is proposed based on the signal-to-noise ratio of the concentration time curve at maximum concentration (SNRC). Monte Carlo simulations were used to determine the optimal threshold for different SNRC. This technique was used to analyze data from six healthy volunteers, resulting in a mean gray to white matter cerebral blood flow ratio of 2.67 +/- 0.07. This value is in excellent agreement with values published in the literature.

Blood Flow Velocity↗
PubMed1999

Dynamic redistribution of calmodulin in HeLa cells during cell division as revealed by a GFP-calmodulin fusion protein technique.

It has been suggested by many studies that Ca2+ signaling plays an important role in regulating key steps in cell division. In order to study the down stream components of calcium signaling, we have fused the gene of calmodulin (CaM) with that of green fluorescent protein (GFP) and expressed it in HeLa cells. The GFP-CaM protein was found to have similar biochemical properties as the wild-type CaM, and its distribution was also similar to that of the endogenous CaM. Using this GFP-tagged CaM as a probe, we have conducted a detailed examination of the spatial- and temporal-dependent redistribution of calmodulin in living mammalian cells during cell division. Our major findings are: (1) high density of CaM was found to distribute in two sub-cellular locations during mitosis; one fraction was concentrated in the spindle poles, while the other was concentrated in the sub-membrane region around the cell. (2) The sub-membrane fraction of CaM became aggregated at the equatorial region where the cleavage furrow was about to form. The timing of this localized aggregation of CaM was closely associated with the onset of cytokinesis. (3) Using a TA-CaM probe, we found that the sub-membrane fraction of CaM near the cleavage furrow was selectively activated during cell division. (4) When we injected a CaM-specific inhibitory peptide into early anaphase cells, cytokinesis was either blocked or severely delayed. These findings suggest that, in addition to Ca2+ ion, CaM may represent a second signal that can also play an active role in determining the positioning and timing of the cleavage furrow formation.

Calmodulin↗
PubMed1999

Altered hypothalamic function in response to glucose ingestion in obese humans.

The hypothalamus plays a central role in the regulation of energy intake and feeding behavior. However, the presence of a functional abnormality in the hypothalamus in humans that may be related to excess energy intake and obesity has yet to be demonstrated in vivo. We, therefore, used functional magnetic resonance imaging (fMRI) to monitor hypothalamic function after oral glucose intake. The 10 obese (34 +/- 2 years of age, BMI 34.2 +/- 1.3 kg/m2) and 10 lean (32 +/- 4 years of age, BMI 22.0 +/- 0.9 kg/m2) subjects with normal glucose tolerance ingested 75 g of glucose while a midsagittal slice through the hypothalamus was continuously imaged for 50 min using a conventional T2*-weighted gradient-echo pulse sequence. After glucose ingestion, lean subjects demonstrated an inhibition of the fMRI signal in the areas corresponding to the paraventricular and ventromedial nuclei. In obese subjects, this inhibitory response was markedly attenuated (4.8 +/- 1.3 vs. 7.0 +/- 0.6% inhibition, P < 0.05) and delayed (9.4 +/- 0.5 vs. 6.4 +/- 0.5 min, P < 0.05) compared with that observed in lean subjects. The time taken to reach the maximum inhibitory response correlated with the fasting plasma glucose (r = 0.75, P < 0.001) and insulin (r = 0.47, P < 0.05) concentrations in both lean and obese subjects. These results demonstrate in vivo, for the first time, the existence of differential hypothalamic function in lean and obese humans that may be secondary to obesity.

Adult↗
PubMed1998

Water permeation barrier in isolated cutaneous newborn rat epidermis.

Abnormal water barrier function occurs in irritated skin and certain cutaneous diseases. Methods have been compared for separating the epidermis (site of the barrier) from the whole skin without disturbing the barrier function. The epidermis was separated from newborn rat skin by (1) exposure to 10% trypsin at 4 degrees C for 16 h, (2) exposure to 0.2% dispase at 4 degrees C for 16 h, (3) heating for 50 s at 55 degrees C, (4) or heating for 40 s at 50 degrees C after the whole skin was kept in medium at the air-liquid interface for 1 day at 35 degrees C. Water permeation of the isolated epidermis was then measured immediately or after 3, 5, 8, and 10 days of maintenance at the air-liquid interface. The water permeation barrier constant (kp) was 1.9+/-0.9 cm/h in intact rat skin. At 0 day of maintenance, the kp of the epidermis was 2.1+/-0.9 after treatment with trypsin, 3.8+/-1.2 after dispase, and 4.3+/-1.4 after immediate heating, or 2.2+/-0.7 cm/h after culture and heating. The dispase and heating methods disrupted the barrier to a greater extent than did the trypsin and culture-heating methods. The latter two methods allowed the kp to be maintained at low levels for 8 days (kp for trypsin 2.8+/-0.9 and 2.5+/-0.8 for culture-heating). Epidermis isolated by the trypsin or culture-heating techniques and maintained at the air-liquid interface can be used to study the mechanism by which barrier function is disrupted by chemicals.

Animals↗
PubMed1997

[The value of salivary beta 2 microglobulin concentration for diagnosis of Sjögren's syndrome].

In this paper we measured salivary beta 2 microglobulin (beta 2 m) concentration in 40 patients with Sjögren's syndrome, including 20 patients with systemic lupus erythematosus, 12 patients with recurrent aphthous ulceration and 16 patients with single xerostomia, and in 40 normal controls. The results showed that salivary beta 2 m concentration was more significantly elevated in Sjögren's syndrome patients, compared with that in both normals and other patients. The measurement of beta 2 m concentration in saliva may offer a simple and valuable method for diagnosis of Sjögren's syndrome.

Adult↗
PubMed1996

Structural motifs encoded by individual exons of the human neurokinin-1 receptor gene interact differentially with selective agonists and antagonists.

Three chimeric receptors were constructed by exchanging exons between human neurokinin NK1 and NK3 receptor genes. The N-terminal sequences of these chimeric receptors are encoded by exon 1, exon 1-2, or exon 1-3 of the NK1 receptor gene, whereas the remaining C-terminal sequences of these chimeric receptors are encoded by corresponding exons of the human NK3 receptor gene. Substance P bound with high affinities to all three chimeric receptors, suggesting that in addition to the common structures composed of conserved amino acid residues among neurokinin receptors, structural elements encoded by the first exon of the human NK1 receptor gene may also play an important role for substance P binding. On the contrary, potent NK1 antagonists L703,606 and SR140,333 did not show any detectable binding to these chimeric receptors. In accordance, sequences encoded by exon 4, and possibly exon 5, are likely to contain important structural motifs that may directly or indirectly influence the binding of these antagonists. Further comparison of the binding affinities of highly selective NK1 agonists, [Sar9, Met(O2)11] substance P, substance P methyl ester, and septide, revealed that each agonist may interact differently with the human NK1 receptor. These results show that the exon-exchanging technique can be a useful tool for studying structure-function relationships of receptors in which exon-intron junctions are fully conserved among receptor subtypes.

Amino Acid Sequence↗
PubMed1996

[Secretion of endothelin-1 by cultured human normal adrenal cells].

Endothelin (ET) is a vasoactive peptide produced by some other types of cells in addition to endothelial cells. The authors investigated into the possibility of ET-1 secretion by cultured human normal adrenal cells. Human normal adrenal cells were prepared by 2% collagenase digestion for 1.5 hours and cultured in DMEM supplemented with 10% FCS. Angiotensin I (10(-9)-10(-7) mol/L) was added to the experimental groups on the 7-9th days of cultivation. Mediums were collected after 24 hours and the levels of aldosterone, cortisol and ET-1 in the mediums were measured by RIA. Other than aldosterone and cortisol, ET-1 was detected in the cultured mediums of human normal adrenal cells. And the secretion of ET-1 was stimulated by angiotesin I. Therefore, it is proposed that ET-1 may play a role by autocrine or paracrine in the human normal adrenal gland.

Adrenal Glands↗
PubMed1995

Growing a stratified, cornified primary culture of rat keratinocytes with epidermis-like water permeation barrier function.

The culture of cutaneous keratinocytes grown on a Puropore nylon microporous membrane at the air-liquid interface has been shown to be similar to the epidermis in a number of molecular and morphologic characteristics but to exhibit a significantly greater degree of tritiated water permeation. Various culture conditions have been altered in an effort to improve the water barrier properties. A Kp value in the range of 5.5 +/- 1.6 x 10(3) has been obtained for 79% of the cultures a) by plating 0.9 x 10(6) viable basal cells on a piece (13-mm diameter) of membrane for 7 days of submerged growth, b) by placing two membranes on two stacked glass fiber filters (47-mm extra-thick) in a culture dish (60 mm) for 14 days of growth at the air-liquid interface, c) by replacing the growth medium, i.e., 1 ml of complete minimum essential medium (CMEM) every 24 h after lifting, d) by using 10% fetal bovine serum (FBS) in the CMEM during the submerged culture period and 15% FBS in the CMEM during the lifted culture period, and e) by adding a dialysis membrane on top and a Puropore nylon membrane below the culture when the cultures were inserted in the permeation cell for testing. The percentage of cultures with this value for Kp can be increased to 90% if only cultures with yellow, smooth, and shiny surfaces are tested. This system should be useful as a replacement for skin in testing the cutaneous permeation of some chemicals.

Animals↗
PubMed1995

Use of human pseudo-epidermis to evaluate the toxicity of bis-(2-chloroethyl)sulfide (BCES) on water permeation barrier formation and function.

Human pseudo-epidermis was used to investigate the effects of bis-(2-chloroethyl)sulfide (BCES) on the formation and function of the water permeation barrier. To generate the culture, 2 million viable basal cells derived from human skin were placed on a Puropore nylon microporous membrane pre-coated with calf skin collagen. Addition of bovine pituitary extract and epidermal growth factor to the medium favored the formation of homogeneous cultures and better barrier function. The water permeation constant (Kp) was shown to decrease significantly and reached 25 +/- 6 x 10(-3) when it was calculated from 71% of the cultures prepared. The effects of topically applied BCES on the incorporation of [14C]linoleic acid, as a marker for lipid synthesis, and Kp, as a measure of water permeation, were studied. Compared with untreated cultures, there was no difference in the Kp immediately after exposure to 1-10 nmol BCES/cm2 for 30 min. On the other hand, [14C]linoleic acid incorporation was dose-dependently decreased immediately after exposure and then returned to normal by 48 h later. These data suggest that BCES produces no direct damage to the water permeation barrier but may affect barrier formation by inhibiting lipid synthesis.

Adult↗
PubMed1995

[Effects of 3 kinds of decoction on serum gastrin, gastrin cell density and the content of PGE2 of gastric antral mucosa in experimental chronic gastritis in rats].

Experimental chronic gastritis (ECG) models were established in rats by inserting a spring into pyloric canal as well as feeding sodium deoxycholate. An experiment was undertaken to observe the therapeutic effects of three formulas of traditional Chinese medicine "Shipitong" (SPT), "Ganpingyangwei" (GPYW) and "Weile" (WL). The experimental results show that all of the three decoctions can make serum gastrin, gastrin cell density and amount of antral mucosal PGE2 of the ECG rats return to normal levels.

Animals↗
PubMed1995

[Effects of three kinds of decoction on histopathology of gastric mucosa, gastric pH and the content of bile acid in experimental chronic gastritis in rats].

Experimental chronic gastritis (ECG) models were established in rats by inserting a spring into pyloric canal as well as feeding sodium deoxycholate. An experiment was undertaken to observe the therapeutic effects of three formulas of traditional Chinese medicine "Shipitong", "Ganpingyangwei" and "Weile". The experimental results show that all of the three decoctions can reduce gastric pH and bile acid of the ECG rats and make gastric mucosal histomorphology of these rats change markedly.

Animals↗
PubMed1994

A comparative study usefulness of magnetic resonance imaging in the diagnosis of acute cholecystitis.

The utility of magnetic resonance imaging (MRI) in the diagnosis of acute cholecystitis was evaluated in 72 consecutive individuals (5 healthy, 13 with chronic cholecystitis and silent gallbladder stones, 43 without biliary or diffuse liver disease, and 11 with acute cholecystitis and gallbladder stones) with a 0.5-T superconducting unit. On the T1-weighted (500/20) and less T1-weighted axial spin-echo images (620/25), the liver/gallbladder signal intensity ratio (mean +/- SD) was 2.5 +/- 0.51 (n = 5) and 1.8 +/- 0.29 (n = 8) in acute cholecystitis; 0.9 +/- 0.42 (n = 6) and 1.0 +/- 0.29 (n = 9) in chronic cholecystitis; and 0.9 +/- 0.14 (n = 5) and 0.8 +/- 0.19 (n = 43) in normal gallbladder, respectively. Our results indicate that the liver/gallbladder signal intensity ratio on the T1-weighted image may be a simple and reliable indicator for the diagnosis of acute cholecystitis; we suggest further investigation to confirm these results.

Acute Disease↗