Biomedical subjects

S Tian

Publications and source records attributed to S Tian.

At least 19 recordsLinked to original sources

PubMed2006

Rapid eye movement sleep deprivation selectively impairs recall of fear extinction in hippocampus-independent tasks in rats.

Previous studies have shown that rapid eye movement (REM) sleep deprivation (RSD) exerts a detrimental effect on some memory tasks. However, whether post-learning RSD impairs memory for fear extinction, an important model of inhibitory learning, remains to be elucidated. The present study examined the effects of post-extinction RSD from 0 to 6 h and 6 to 12 h on recall of fear extinction tested 24 h after extinction training. We found that RSD from 0 to 6 h significantly increased freezing when recall of extinction of cued fear was tested in the context in which rats received extinction training whereas RSD from 6 to 12 h had no effect (experiments 1 and 2, two hippocampus-independent memory tasks). RSD at either time point had no effect on freezing when recall of extinction of cued fear was tested in the context different from that in which extinction training occurred (experiment 3, a hippocampus-dependent memory task). Additionally, we observed no effect of RSD at either time point on freezing during recall test for extinction of contextual fear (experiment 4, a hippocampus-dependent memory task). These results suggest that the effects of post-extinction RSD on memory for fear extinction are complex. RSD impairs recall of fear extinction in hippocampus-independent tasks, but does not affect recall of fear extinction in hippocampus-dependent tasks. Our findings extend previous research on the effects of RSD on learning and memory and support the notion that REM sleep is involved in memory process of certain tasks.

Acoustic Stimulation↗

PubMed2005

Dynamic changes in orbitofrontal neuronal activity in rats during opiate administration and withdrawal.

The orbitofrontal cortex is involved in the reinforcing effects of drugs of abuse. However, how the dynamic activity in OFC changes during opiate administration and withdrawal period has not been investigated. We first tested the effects of opiates and drug craving with the conditioned place preference paradigm, using manganese-enhanced magnetic resonance imaging and traditional electroencephalograph recording techniques in rats. T1-weighted 2D MRI (4.7 T) was used after unilateral injection of MnCl(2) (200 nL, 80 mM) into the right orbitofrontal cortex. The manganese-enhanced magnetic resonance imaging data suggested that the OFC activity decreased during the opiate administration period but recovered increasingly during the withdrawal period. Also, we found decreases and increases in gamma-band (20-100 Hz) activity during the opiate administration and withdrawal period, respectively. Our results showed that orbitofrontal cortex activity decreased during morphine administration and then went up progressively over several days during withdrawal. The time course of the recovery of orbitofrontal activity from inhibition during the withdrawal period may be related to the experience of drug craving.

Animals↗

PubMed2002

Cognitive impairment in Parkinson's disease revealed by event-related potential N270.

Disturbed cognitive function is a well-recognized feature of idiopathic Parkinson's disease (PD). The aim of this study was to find a susceptive index to reveal the minor cognitive impairment in PD patients. Thirty PD patients without clinical dementia and thirty-four age-matched normal controls performed a matching task while event-related potentials (ERPs) were recorded from their scalp. There were two kinds of stimulus pairs in this study: match condition, the second stimulus (S2) in a pair was identical to the first one (S1); conflict condition, S2 conflicted with S1 in the color attribute. Subjects were required to press a button in the match condition and another button in the conflict condition. A negative ERP component, N270, which was considered to reflect the conflict processing activity in human brain, was evoked by the S2 of the conflict condition. The patient group showed a delayed and smaller N270 than the control group. The prolongation of its peak latency was significant at P3 and P4 electrodes and the reduction of its mean amplitude was significant at P3 electrode. The amplitude of P300 elicited in the match condition was decreased in the patient group at P4 electrode but its latency did not differ from the control group. These results indicate that PD patients as a group showed cognitive decline even in the absence of clinical dementia. N270 is a sensitive index in revealing this minor cognitive impairment.

Adult↗

PubMed2002

Stabilization of breast cancer xenograft tumour neovasculature by angiopoietin-1.

Angiopoietin-1 is a promoter of physiological vasculogenesis and angiogenesis because it induces vascular branching and smooth muscle recruitment to newly formed blood vessels. However, angiopoietin-1 expression in tumours appears to be uncommon, and angiopoietin-1 overexpression in cancer cells has been reported to lead to inhibition of xenograft tumour growth. We report here that angiopoietin-1 overexpression resulted in stabilization of tumour edge-associated blood vessels, as it prevented vessel dilation and dissociation of smooth muscle cells from existing vessels. In addition, angiopoietin-1 stimulated an infiltration of mesenchymal cells into the tumours, such that the coverage of microvessels by pericytes increased markedly, and the cancer cells were separated into small masses by the host stroma. The rates of both cancer cell proliferation and apoptosis decreased significantly in the presence of angiopoietin-1. Tie2, the receptor for angiopoietin-1, was found to be present in vascular smooth muscle cells in culture in addition to endothelial cells. These findings suggest that a vascular stabilization effect of angiopoietin-1 accounts for the inhibition of tumour growth.

Angiopoietin-1↗

PubMed2001

Modulation of endothelial cell growth arrest and apoptosis by vascular endothelial growth inhibitor.

Vascular endothelial growth inhibitor (VEGI), a new member of the tumor necrosis factor family, is an endothelial cell-specific gene and a potent inhibitor of endothelial cell proliferation, angiogenesis, and tumor growth. We report here that VEGI mediates the following two activities in endothelial cells: early G(1) arrest in G(0)/G(1) cells responding to growth stimuli, and programmed death in proliferating cells. G(0)/G(1)-synchronized bovine aortic endothelial cells were treated with VEGI before and after the onset of the growth cycle. When the cells were stimulated with growth conditions but treated simultaneously with VEGI, a reversible, early-G(1) growth arrest occurred, evidenced by the lack of late G(1) markers such as hyperphosphorylation of the retinoblastoma gene product and upregulation of the c-myc gene. Additionally, VEGI treatment led to inhibition of the activities of cyclin-dependent kinases CDK2, CDK4, and CDK6. In contrast, VEGI treatment of cells that had entered the growth cycle resulted in apoptotic cell death, as evidenced by terminal deoxytransferase labeling of fragmented DNA, caspase 3 activation, and annexin V staining, all of which were lacking in nonproliferating cells treated with VEGI. Additionally, stress-signaling proteins p38 and JNK were not as fully activated by VEGI in quiescent as compared with proliferating populations. These findings suggest a dual role for VEGI, the maintenance of growth arrest and induction of apoptosis, in the modulation of the endothelial cell cycle.

Animals↗

PubMed2001

Different processes are involved in human brain for shape and face comparisons.

Fifteen subjects participated in a matching task of visual stimuli. Two sequentially presented stimuli in a pair were the same shape (shape match), different shapes (shape mismatch), same human face (face match) or different faces (face mismatch). All four kinds of stimulus pairs were of equal probability. The shape mismatch pairs elicited a negative event-related potential component N270 (Peak latency: 262.1+/-16.5 ms, P4) after the second stimulus onset, while the face mismatch evoked N270 with longer peak latency (301.2+/-19.8 ms, P4) and N450. There exists a specific system for mismatch processing of a complex stimulus (face) in the human brain.

Cerebral Cortex↗

PubMed2001

[Transporting into the kidney of medications injected into the renal adipose capsules of rats].

OBJECTIVE: To study the possibility of transporting into the renal tissue of medications by intrarenal adipose capsule injection (IC). METHODS: 1. Methylene blue (MB) was injected into the renal adipose capsule of 18 male healthy SD rats, and normal saline was injected into the renal adipose capsule at the side as control. Both kidneys taken out 1 - 24 hours after the injection, frozen slices were made to observe the transport of MB. 2. Salvia miltiorrhizae (SM) was injected into both renal adipose capsule of 18 male healthy SD rats. 48 healthy male SD rats were randomly divided into two groups, Tetramethylpyrazine (20 mg) was injected into per renal adipose capsule of the rats in one group and 40 mg Tetramethylpyrazine (TP) was injected into the veins of the rats in another group. 64 SD rats were randomly divided into two groups, methylprednisolone sodium succinate (25 mg/kg) was injected into per renal adipose capsule of the rats in one group and 50 mg/kg methylprednisolone (MP) sodium succinate was injected into the veins of the rats in another group. At different time, both kidneys and blood samples of all the rats were taken out. The contents of the three medications inside renal tissue and its blood samples were individually detected by HPLC. RESULTS: The peak values in the renal tissue of MB, SM, TP, MP were successively 6 h, 24 h (36 mg/g +/- 18 mg/g), 12 h (2 288 microgram/g +/- 236 microgram/g) and 1 h (120 microgram/g +/- 16 microgram/g) after IC. The medicine diffusing into the kidney can maintain longer time in IC group. CONCLUSION: The renal adipose capsule can be acted as the place of medicine storing and releasing into the kidney. The medicine diffusing into the kidney can attain higher concentration and maintain longer time. IC is a feasible method of local renal ad ministration with much less side effects.

Adipose Tissue↗

PubMed2001

Enhancement of conflict processing activity in human brain under task relevant condition.

To investigate the working mechanism of the conflict processing system, pairs of colored numbers were sequentially presented on a screen to subjects. They were asked to determine if the magnitude or the color of the two numbers was identical. Event-related potentials (ERPs) were recorded at the same time. A negative potential peaking at 270 ms (N270) after the onset of the second number (S2) was elicited when S2 conflicted with the first number (S1) in task-relevant and (or) irrelevant attribute conflicts. The mean amplitude of the N270 was more negative in task relevant conflict than in irrelevant conflict. Therefore, the conflict processing activity can be initiated independently of the task, but is enhanced in task relevant conflict.

Adult↗

PubMed2001

MRI measurements of orbital tissues in dysthyroid ophthalmopathy.

BACKGROUND: Muscle volume investigation by different imaging techniques has proven useful in the diagnosis and follow up of treatment in dysthyroid ophthalmopathy. However, no study on muscle volume measurement by magnetic resonance imaging (MRI) has been done in this disease. METHODS: Six patients with monocular or asymmetric binocular dysthyroid ophthalmopathy and eight controls were examined with orbital MRI using a surface coil. In the muscle volume study, 2 mm coronal slices were used for measuring the six extraocular muscles (EOM), i.e., medial rectus (MR), lateral rectus (LR) superior rectus (SR), inferior rectus (IR), superior oblique (SO), and inferior oblique (IO) muscles, as well as the orbital fatty tissue (OFT). In the muscle thickness study, 3 mm transverse and sagittal images were used for measuring the four rectus muscles during fixation in different gaze positions in horizontal and vertical planes. RESULTS: In dysthyroid ophthalmopathy, the muscle volume of the six external eye muscles was significantly larger than in controls, except for the IO. The IR and MR showed the largest increase in muscle volume. The correlation between muscle thickness and different degrees of eye deflections was linear for all four rectus muscles both in patients and controls, and no significant differences in the slopes of the regression lines were found. The volume of OFT was significantly larger in patients than in controls, and the change in volume was larger than that of muscle volume. CONCLUSIONS: MRI technique makes it possible to observe and evaluate quantitatively the volume of all six extraocular muscles and the orbital fatty tissue in dysthyroid ophthalmopathy. It also makes it possible to evaluate changes in morphology during eye muscle contraction.

Adipose Tissue↗

PubMed2001

Determination of active component in silymarin by RP-LC and LC/MS.

Silybin, isosilybin, silydianin and silycristin in silymarin were separated and quantitatively determined by RP-HPLC. Two diastereoisomers of silybin and isosilybin were respectively separated by RP-HPLC and confirmed by LC/MS. Chromatographic condition consisted of column: Shim-pack VP-ODS (150 x 4.6mm i.d. 5 microm) and Pre-column (10 x 4.6 mm i.d. 5 microm); mobile phase: methanol and solvent mixture (water: dioxane=9:1) by gradient; flow rate: 1.5ml/min; column temp.: 40 degrees C; detector wavelength: 288 nm; The recovery of 99.66% for silycristin, 99.48% for silydianin, 100.0% for silybin and 98.72% for isosilybin was respectively obtained.

Antioxidants↗

PubMed2001

Interstimulus interval effect on event-related potential N270 in a color matching task.

Event-related brain potentials were recorded in a matching task, in which subjects were asked to discriminate if the color of the second stimulus (S2) was the same as the first stimulus (S1). The interstimulus interval between the two stimuli of a pair was of three levels (150 ms, 500 ms and 1000 ms). A negative component about 270 ms after the presentation of S2 was elicited when the color of the two stimuli was not identical for the interstimulus interval of 500 ms and 1000 ms, but not for the interval of 150 ms. This may suggest that N270 represented the response of the brain to conflicting information between different cortical levels.

Adult↗

PubMed2001

[Preparation of green fluorescent protein retrovirus and its application in mediating gene transfer into retinal pigment epithelial cells].

OBJECTIVE: To determine whether human retinal pigment epithelial (RPE) cells can be infected by retrovirus and modified by retrovirus-mediated gene transfer. METHODS: Recombination retroviral vector pLNCX-GFP (green fluorescent protein, GFP) was generated by inserting 780 bp GFP cDNA fragment into the MCS site of pLNCX. pLNCX-GFP was transfected into ecotropic packaging cell line PhiX-Eco and amphotropic packaging cell line PhiX-Ampho and PA317. Retroviral titer was tested by counting GFP expression of NIH3T3 cells. Then RPE cells were infected by using GFP retrovirus-containing supernatant. RESULTS: GFP was expressed and retrovirus was produced upon pLNCX-GFP being transfected into packaging cell line. The GFP retrovirus was able to infect primary cultured human RPE cells and immortalized RPE cell line. CONCLUSION: The retrovirus can introduce a foreign gene into RPE cells efficiently, thereby it can be used as an important tool to deliver gene into RPE for therapy of fundus diseases.

Cells, Cultured↗

PubMed2001

[Clinical evaluation on second stage reconstruction for laryngostenosis after partial laryngectomy for laryngeal cancer patients].

OBJECTIVE: To present a new method of decannulation for laryngostenosis patients after partial laryngectomy and extended partial laryngectomy, and restoration of the essential functions of larynx and normal neck appearance. METHODS: Nineteen cases of laryngostenosis after partial laryngectomy and extended partial laryngectomy were treated with second stage reconstruction. The patients had been treated by vertical laryngectomy (6/19) using extended vertical laryngectomy (11/19) and frontolateral laryngectomy (2/19). Among these patients, second stage reconstruction of larynx was performed by using rotary door myocutaneous flap (17/19). Stemohyoideus flap (1/19) and sternocleidomastoid flap (1/19). RESULTS: Three and five year-survival rates were 91.7% (11/12) and 3/5, respectively. Over-all decannulation rate was 84.2% (16/19), but 94.1% (16/17) in patients with rotary door myocutaneous flap and 0% (0/2) in both patients with sternohyoideus flap and sternocleidomastoid flap. There were 3 decannulation failures (15.8%). All patients resumed acceptable voice, 94.7% (18/19) enjoyed satisfactory phonation, but 5.3% (1/19) showed severe hoarseness. All except 2 patients returned normal swallow function. The latter 2 patients experienced mild abnormal swallow during eating fluid food in early stage of surgery, but had normal swallow function after 1-2 weeks. CONCLUSION: Functional laryngectomy is a radical operation in selected cases with advanced laryngeal cancer. The second stage reconstruction with bi-pedical rotary door myocutaneous flaps can help decannulation in patients who developed laryngostenosis after partial laryngectomy and extended partial laryngectomy, and restore the essential function of larynx and normal neck appearance.

Adult↗

PubMed2001

[Determination of trace cadmium in human hair, fingernail and toenail for ten years by flame atomic absorption spectrometry].

The human hair, fingernail and toenail were collected from one person quarterly for about ten years, respectively thirty-three, forty-one and thirty-nine shares. The contents of traces cadmium in hair, fingernail and toenail have been determined by flame atomic absorption spectrometry, and the results were satisfactory. From a changing curve in human hair, fingernail and toenail cadmium by age, we found that the range of cadmium contents in hair was 0.0100-0.4100 microgram.g-1, in fingernail 0.0295-0.5314 microgram.g-1, in tene-nail 0.0899-1.274 micrograms.g-1, respectively. In the changing curve there is a nonlinear characteristic.

Cadmium↗

PubMed2000

Morphine Up-regulates expression of substance P and its receptor in human blood mononuclear phagocytes and lymphocytes.

In vitro and in vivo studies have indicated that there is an important relationship between morphine and neuropeptide substance P (SP). We therefore investigated the interaction of morphine and cultured human immune cells on the expression of SP, a neuropeptide which we have recently demonstrated to be produced by human monocytes and lymphocytes. Morphine up-regulated SP production in human mononuclear phagocytes and lymphocytes at both the mRNA and the protein level. In addition, morphine induced SP receptor (NK-1R) expression in human lymphocytes. The specific morphine receptor antagonist (naltrexone) blocked morphine-induced SP expression in human mononuclear phagocytes, supporting the concept of authentic morphine receptor-mediated regulation. Since SP modulates neurogenic inflammation and immunologic events, these data suggest that morphine-induced SP expression in cells of the immune system may be of importance in the pathogenesis of immune-mediated diseases, including neuroimmunologic diseases and AIDS.

Adult↗

PubMed2000

Human brain sub-systems for discrimination of visual shapes.

To investigate whether stereo and plane visual shapes are processed in the same brain system, participants were instructed to discriminate whether two visual stimuli presented in sequence were identical and event-related potential (ERP) was recorded from their scalp. The first (S1) and the second stimuli (S2) were the same stereo shapes in condition 1, but were different in condition 3. They were the same plane shapes in condition 2, but different in condition 4. A negative component (N270) was recorded in condition 3 and 4, which showed the maximal amplitude in the right posterior scalp in condition 3 and in the anterior scalp in condition 4. A different cognition mechanism is involved in the processing of non-matched stereo and plane visual shapes.

Adult↗

PubMed2000

Selectively monomodified cyclodextrins. Synthetic strategies

Monomodifications of cyclodextrins to give selectively 2-, 3-, or 6-substituted product is a challenging task because of the number of hydroxyl groups that can potentially react with the incoming reagent. The principles and the methods involved in manipulations of the differences in the chemistry of these hydroxyl groups to control the outcome of an electrophilic reaction with them to produce monoalkylated (ether-linkaged) cyclodextrin derivatives are discussed and illustrated.

Journal Article↗

PubMed2000

Close association of the N terminus of Kv1.3 with the pore region.

The Shaker superfamily encodes voltage-gated potassium (Kv) channels. The N termini of Shaker proteins are located intracellularly and contain several domains shown to regulate important aspects of channel function, such as speed of inactivation, channel assembly (T1 domain), and steady state protein level (T0 domain, amino acids 3-39 in rabbit). Mutations and/or deletion of certain amino acids in the T0 domain lead to a 13-fold amplification of Kv current as compared with wild type channels, primarily by increasing the absolute number of channel proteins present in the membrane (Segal, A. S., Yao, X., and Desir, G. V. (1999) Biochem. Biophys. Res. Commun. 254, 54-64). Although T0 mutants have kinetic properties virtually indistinguishable from wild type, they were noted to have a slightly larger single channel conductance, suggesting that the T0 domain might also interact with the pore region. In the present study we show that although T0 does not affect pore selectivity, it does modulate the binding affinity of the pore blocker, charybdotoxin. These results suggest that the N terminus of Kv1.3 is closely associated with the pore region.

Amino Acid Sequence↗