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Biomedical subjects

D Wang

Publications and source records attributed to D Wang.

At least 325 records · Page 18Linked to original sources
PubMed2000

Antinociceptive role of galanin in periaqueductal grey of rats with experimentally induced mononeuropathy.

The present study was performed in rats with experimentally induced mononeuropathy after left common sciatic nerve ligation. The hindpaw withdrawal latencies to thermal and mechanical stimulation increased significantly after intra-periaqueductal grey injection of 2 or 3nmol, but not 1nmol of galanin in rats with mononeuropathy. Intraperitoneal administration of 4.5mg/kg morphine induced significant increases in hindpaw withdrawal latencies to both noxious stimulation, which were attenuated by following intra-periaqueductal grey injection of 2nmol of the galanin antagonist galantide. Furthermore, the antinociceptive effect induced by intra-periaqueductal grey injection of 26.6nmol of morphine was attenuated significantly by following intra-periaqueductal gray administration of 2nmol of galantide. The results demonstrated that in periaqueductal grey galanin plays an antinociceptive role in rats with mononeuropathy and galanin is involved in the mechanisms of opioid-induced antinociception.

Analgesics↗
PubMed2000

Orientation relationships of martensite variants determined by electron backscatter diffraction

Orientation relationships between the parent phase and 2H type martensite, and between different variants in a plate group of martensite in the CuAlNi shape memory alloy were determined by electron backscatter diffraction. The result reveals clearly that the basal planes of different correspondence variants of the 2H martensite originate from different 110P planes of the parent phase, and the [010]2H axis of each correspondence variant originates from one of the <001>P axes of the parent phase. Our result reveals also the typical relationships of four habit-variants A, B, C and D in a martensite plate group, and that the habit-variants A and C (and equivalenty B and D) are twin-related by an 1212H mirror plane, and the habit-variants A and D (and B and C) are twin-related by an 1012H mirror plane. Usually, variants A and C (and B and D) form spear morphology and variants A and D (and B and C) form fork morphology.

Journal Article↗
PubMed2000

Survival after emergency department thoracotomy: review of published data from the past 25 years.

BACKGROUND: Emergency department thoracotomy (EDT) has become standard therapy for patients who acutely arrest after injury. Patient selection is vitally important to achieve optimal outcomes without wasting valuable resources. The aim of this study was to determine the main factors that most influence survival after EDT. STUDY DESIGN: Twenty-four studies that included 4,620 cases from institutions that reported EDT for both blunt and penetrating trauma during the past 25 years were reviewed. The primary outcomes analyzed were in-hospital survival rates. RESULTS: EDT had an overall survival rate of 7.4%. Normal neurologic outcomes were noted in 92.4% of surviving patients. Factors reported as influencing outcomes were the mechanism of injury (MOI), location of major injury (LOMI), and signs of life (SOL). Survival rates for MOI were 8.8% for penetrating injuries and 1.4% for blunt injuries. When penetrating injuries were further separated, the survival rates were 16.8% for stab wounds and 4.3% for gunshot wounds. For the LOMI, survival rates were 10.7% for thoracic injuries, 4.5% for abdominal injuries, and 0.7% for multiple injuries. If the LOMI was the heart, the survival rate was the highest at 19.4%. The third factor influencing outcomes was SOL. If SOL were present on arrival at the hospital, survival rate was 11.5% in contrast to 2.6% if none were present. SOL present during transport resulted in a survival rate of 8.9%. Absence of SOL in the field yielded a survival rate of 1.2%. There was no clear single independent preoperative factor that could uniformly predict death. CONCLUSIONS: The best survival results are seen in patients who undergo EDT for thoracic stab injuries and who arrive with SOL in the emergency department. All three factors-MOI, LOMI, and SOL-should be taken into account when deciding whether to perform EDT. Uniform reporting guidelines are needed to further elucidate the role of EDT taking into account the combination of MOI, LOMI, and SOL.

Emergencies↗
PubMed2000

Phospholipase Cgamma2 is essential in the functions of B cell and several Fc receptors.

Many receptors activate phospholipase Cgamma1 or -gamma2. To assess the role of PLCgamma2, we derived enzyme-deficient mice. The mice are viable but have decreased mature B cells, a block in pro-B cell differentiation, and B1 B cell deficiency. IgM receptor-induced Ca2+ flux and proliferation to B cell mitogens are absent. IgM, IgG2a, and IgG3 levels are reduced, and T cell-independent antibody production is absent. The similarity to Btk- or Blnk-deficient mice demonstrates that PLCgamma2 is downstream in Btk/Blnk signaling. FcRgamma signaling is also defective, resulting in a loss of collagen-induced platelet aggregation, mast cell FcepsilonR function, and NK cell FcgammaRIII and 2B4 function. The results define a signal transduction pathway broadly utilized by immunoglobulin superfamily receptors.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Stat5 is essential for the myelo- and lymphoproliferative disease induced by TEL/JAK2.

STAT5 is activated in a broad spectrum of human hematologic malignancies. We addressed whether STAT5 activation is necessary for the myelo- and lymphoproliferative disease induced by TEL/JAK2 using a genetic approach. Whereas mice transplanted with bone marrow transduced with retrovirus expressing TEL/JAK2 develop a rapidly fatal myelo- and lymphoproliferative syndrome, reconstitution with bone marrow derived from Stat5ab-deficient mice expressing TEL/JAK2 did not induce disease. Disease induction in the Stat5a/b-deficient background was rescued with a bicistronic retrovirus encoding TEL/JAK2 and Stat5a. Furthermore, myeloproliferative disease was induced by reconstitution with bone marrow cells expressing a constitutively active mutant, Stat5a, or a single Stat5a target, murine oncostatin M (mOSM). These data define a critical role for Stat5a/b and mOSM in the pathogenesis of TEL/JAK2 disease.

Animals↗
PubMed2000

Synthesis of starlike N-(2-hydroxypropyl)methacrylamide copolymers: potential drug carriers.

Starlike HPMA copolymers were synthesized by conjugating semitelechelic poly[N-(2-hydroxypropyl)-methacrylamide] macromolecules (ST-PHPMA, arm) with PAMAM dendrimers (core: G2, G3, G4). ST-PHPMA was synthesized by chain transfer free radical polymerization, and the terminal -COOH was activated with N-hydroxysuccinimide. Doxorubicin (DOX) was introduced into the starlike HPMA copolymer to evaluate its potential as a drug delivery system. The polymers were characterized with SEC, NMR, and UV. Cytotoxicity of the DOX containing starlike HPMA copolymer was determined on an A2780 human ovarian carcinoma cell line and compared with DOX-containing linear HPMA copolymers. The rate of in vitro DOX release from polymer--DOX conjugates in the presence of cathepsin B (CP-B, lysosomal cysteine proteinase) was determined and correlated with cytotoxicity results.

Antibiotics, Antineoplastic↗
PubMed2000

Analysis of glycosidically bound aroma precursors in tea leaves. 1. Qualitative and quantitative analyses of glycosides with aglycons as aroma compounds.

Twenty-six synthetic glycosides constituting aglycons of the main tea aroma compounds ((Z)-3-hexenol, benzyl alcohol, 2-phenylethanol, methyl salicylate, geraniol, linalool, and four isomers of linalool oxides) were synthesized in our laboratory as authentic compounds. Those compounds were used to carry out a direct qualitative and quantitative determination of the glycosides as aroma precursors in different tea cultivars by capillary gas chromatographic-mass spectrometric (GC-MS) analyses after trifluoroacetyl conversion of the tea glycosidic fractions. Eleven beta-D-glucopyranosides, 10 beta-primeverosides (6-O-beta-D-xylopyranosyl-beta-D-glucopyranoside) with aglycons as the above alcohols, and geranyl beta-vicianoside (6-O-alpha-L-arabinopyranosyl-beta-D-glucopyranoside) were identified (tentatively identified in the case of methyl salicylate beta-primeveroside) in fresh tea leaves and quantified on the basis of calibration curves that had been established by using the synthetic compounds. Primeverosides were more abundant than glucosides in each cultivar we investigated for making green tea, oolong tea, and black tea. Separation of the diastereoisomers of linalool and four isomers of linalool oxides by GC analyses is also discussed.

Calibration↗
PubMed2000

Physical and personality traits of preschool children in Fuzhou, China: only child vs sibling.

Concern about the healthy growth and development of an only child has been voiced since the 1970s, when the Chinese government launched the only child policy. In this study, the physical and personality traits of rural Chinese preschool only-children (onlies) whose age ranged from 3 to 6 years old were evaluated. The sample included 197 onlies and 367 children with siblings who came from seven kindergartens in rural areas in Fuzhou, Fujian province. The results showed no statistically significant differences in height, mass or BMI between the onlies and siblings. Regarding the personality traits, the significant difference was that the onlies exhibited more somatic complaints, however, the data didn't indicate any other undesirable personality traits for the onlies. These results suggest that Chinese preschool children grow normally with or without siblings.

Body Height↗
PubMed2000

Prevention of a chronic progressive form of experimental autoimmune encephalomyelitis by an antibody against mucosal addressin cell adhesion molecule-1, given early in the course of disease progression.

A role for alpha4 and beta7 integrins in mediating leucocyte entry into the central nervous system in the multiple sclerosis (MS)-like disease experimental autoimmune encephalomyelitis (EAE) has been demonstrated. However, the individual contributions of their respective ligands mucosal addressin cell adhesion molecule-1 (MAdCAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-cadherin expressed on the blood-brain barrier has not been determined. In the present paper, it is shown that an antibody directed against MAdCAM-1, the preferential ligand for alpha4beta7, effectively prevented the development of a progressive, non-remitting, form of EAE, actively induced by injection of myelin oligodendrocyte glycoprotein peptide (MOG(35-55)) autoantigen. Combinational treatment with both anti-MAdCAM-1, VCAM-1, and intercellular adhesion molecule-1 (ICAM-1) (ligand for integrin lymphocyte function-associated antigen (LFA)-1) mAbs led to more rapid remission than that obtained with anti-MAdCAM-1 antibody alone. However, neither MAdCAM-1 monotherapy, nor combinational antibody blockade was preventative when administered late in the course of disease progression. In conclusion, MAdCAM-1 plays a major contributory role in the progression of chronic EAE and is a potential therapeutic target for the treatment of MS. Critically, antivascular addressin therapy must be given early in the course of disease prior to the establishment of irreversible damage if it is to be effective, as a single treatment modality.

Animals↗
PubMed2000

Nuclear Ca2+/calmodulin translocation activated by mu-opioid (OP3) receptor.

Previous evidence has suggested a role for calmodulin (CaM) in opioid receptor signaling. We demonstrate here that morphine stimulation of the mu-opioid (OP3) receptor causes rapid CaM translocation to the nucleus in OP3-transfected human embryonic kidney (HEK)-293 cells and in SH-SY5Y human neuroblastoma cells. Ca2+ influx into the cells resulting from OP3 receptor activation was required for nuclear CaM translocation. Moreover, in HEK-OP3 and SH-SY5Y cells, increased nuclear CaM content was associated with enhanced phosphorylation of the nuclear transcription factor cyclic AMP-responsive element-binding protein. This appeared to be mediated by Ca2+/CaM kinases and also by a pathway involving protein kinase C. CaM was previously shown to bind directly to the OP3 receptor and to be released from the plasma membrane on agonist stimulation. To test whether OP3-mediated CaM release contributes to nuclear CaM signaling, we used a mutant OP3 receptor (K273A) with reduced affinity for CaM that fails to release CaM from the plasma membrane. K273A-OP3 activated Ca2+ influx to a similar extent as wild-type OP3; however, CaM translocation to the nucleus was attenuated. These results indicate that OP3-stimulated Ca2+ influx results in nuclear CaM translocation, which appears to be enhanced by simultaneous CaM release by OP3 wild-type receptor from plasma membranes. These results suggest a novel Ca2+/CaM signaling pathway of opioid receptors in the regulation of transcriptional activity.

Animals↗
PubMed2000

Calmodulin regulation of basal and agonist-stimulated G protein coupling by the mu-opioid receptor (OP(3)) in morphine-pretreated cell.

Calmodulin (CaM) has been shown to suppress basal G protein coupling and attenuate agonist-stimulated G protein coupling of the mu-opioid receptor (OP(3)) through direct interaction with the third intracellular (i3) loop of the receptor. Here we have investigated the role of CaM in regulating changes in OP(3)-G protein coupling during morphine treatment, shown to result in CaM release from plasma membranes. Basal and agonist-stimulated G protein coupling by OP(3) was measured before and after morphine pretreatment by incorporation of guanosine 5'-O-(3-[(35)S]thiotriphosphate) into membranes, obtained from HEK 293 cells transfected with human OP(3) cDNA. The opioid antagonist beta-chlornaltrexamine fully suppressed basal G protein coupling of OP(3), providing a direct measure of basal signaling. Pretreatment of the cells with morphine enhanced basal G protein coupling (sensitization). In contrast, agonist-stimulated coupling was diminished (desensitization), resulting in a substantially flattened morphine dose-response curve. To test whether CaM is involved in these changes, we constructed OP(3)-i3 loop mutants with reduced affinity for CaM (K273A, R275A, and K273A/R275A). Basal signaling of these mutant OP(3) receptors was higher than that of the wild-type receptor and, moreover, unaffected by morphine pretreatment, whereas desensitization to agonist stimulation was only slightly attenuated. Therefore, CaM-OP(3) interactions appear to play only a minor role in the desensitization of OP(3). In contrast, release of CaM from the plasma membrane appears to enhance the inherent basal G protein coupling of OP(3), thereby resolving the paradox that OP(3) displays both desensitization and sensitization during morphine treatment.

Amino Acid Substitution↗
PubMed2000

Glycoprotein IIb/IIIa receptor inhibitor attenuates platelet aggregation induced by thromboxane A2 during in vitro nonpulsatile ventricular assist circulation.

A recent development in antithrombotic research allows the inhibition of platelet aggregation via protection of the glycoprotein IIb/IIIa receptor on the platelet membrane. We hypothesized that a GP IIb/IIIa receptor inhibitor would inhibit thromboxane-induced platelet aggregation during circulation in our in vitro ventricular assist device (VAD) circuit and preserve long-term platelet function. Twenty-one in vitro nonpulsatile centrifugal VAD circuits were simulated for 4 days using 450 ml of fresh human whole blood with or without glycoprotein IIb/IIIa receptor inhibitor (tirofiban). Platelet aggregation and degranulation were measured in whole blood induced by ristocetin, collagen, ADP, and thromboxane A2 (TXA2). The tirofiban-treated group preserved the platelet count and tended to exert these beneficial effects by inhibiting pathologic platelet aggregation induced by TXA2, collagen, and ADP as well as degranulation. Tirofiban may be useful in preserving platelet number and function during clinical VAD use.

Adenosine Diphosphate↗
PubMed2000

Engineered bone development from a pre-osteoblast cell line on three-dimensional scaffolds.

Bone regeneration is based on the hypothesis that healthy progenitor cells, either recruited or delivered to an injured site, can ultimately regenerate lost or damaged tissue. Three-dimensional porous polymer scaffolds may enhance bone regeneration by creating and maintaining a space that facilitates progenitor cell migration, proliferation, and differentiation. As an initial step to test this possibility, osteogenic cells were cultured on scaffolds fabricated from biodegradable polymers, and bone development on these scaffolds was evaluated. Porous polymer scaffolds were fabricated from biodegradable polymers of lactide and glycolide. MC3T3-E1 cells were statically seeded onto the polymer scaffolds and cultured in vitro in the presence of ascorbic acid and beta-glycerol phosphate. The cells proliferated during the first 4 weeks in culture and formed a space-filling tissue. Collagen messenger RNA levels remained high in these cells throughout the time in culture, which is consistent with an observed increase in collagen deposition on the polymer scaffold. Mineralization of the deposited collagen was initially observed at 4 weeks and subsequently increased. The onset of mineralization corresponded to increased mRNA levels for two osteoblast-specific genes: osteocalcin and bone sialoprotein. Culture of cell/polymer constructs for 12 weeks led to formation of a three-dimensional tissue with architecture similar to that of native bone. These studies demonstrate that osteoblasts within a three-dimensional engineered tissue follow the classic differentiation pathway described for two-dimensional culture. Polymer scaffolds such as these may ultimately be used clinically to enhance bone regeneration by delivering or recruiting progenitor cells to the wound site.

3T3 Cells↗
PubMed2000

Chemosensitive conductance and inositol 1,4,5-trisphosphate-induced conductance in snake vomeronasal receptor neurons.

Snake vomeronasal receptor neurons in slice preparations were studied using the patch-clamp technique in the conventional and nystatin-perforated whole-cell configurations. The mean resting potential was approximately -70 mV; the average input resistance was 3 GOmega. Neurons required current injection of only 1-10 pA to display a variety of spiking patterns. Intracellular dialysis of 100 microM inositol 1,4,5-trisphosphate (IP(3)) evoked an inward current in 38% of neurons, with an average peak amplitude of 16.4 +/- 2.8 pA at a holding potential of -70mV. Application of 100 microM 3-deoxy-3-fluoro-D-myo-inositol 1,4,5-trisphosphate (F-IP(3)), a derivative of IP(3), also evoked an inward current in 4/8 (50%) neurons (32.6 +/- 58 pA at -70 mV, n = 4). The reversal potentials of the induced components were estimated to be -14 +/- 5 mV for IP(3) and -17 +/- 3 mV for F-IP(3). Bathing the neurons in 10 microM ruthenium red solution greatly reduced the IP(3)-evoked inward current to 1.6 +/- 1.1 pA at -70 mV (n = 6). With Cs(+)-containing internal solution, neither the Ca(2+)-ATPase inhibitor thapsigargin (1-50 microM) nor the Ca(2+)-ionophore ionomycin (10 microM) evoked a significant current response, suggesting that IP(3) can elicit current response in the neurons without mediation by intracellular Ca(2+) stores. Intracellular application of 1 mM cAMP evoked no detectable current response. Extracellular application of chemoattractant for snakes evoked a very large inward current. The reversal potential of the chemoattractant-induced current was similar to that of the IP(3)-induced current. The present results suggest that IP(3) may act as a second messenger in the transduction of chemoattractants in the garter snake vomeronasal organ.

Animals↗
PubMed2000

Amplitude correction in image deconvolution for determining crystal defects at atomic level

A method is proposed to improve the image deconvolution technique based on the weak-phase object approximation for determining the crystal defects at atomic level. Originally, both the amplitude and phase modulation caused by the contrast transfer function (CTF) was removed for all reflections in the diffractogram of the image and then the deconvoluted image was obtained by carrying out the inverse FT. In this paper after removing the CTF modulation the amplitudes of reflections are further corrected by constraining the integral amplitudes to be equal to the corresponding structure factor amplitudes of perfect crystals. [110] high-resolution electron microscope images were simulated for a structure model of Si crystal containing the 60 degrees dislocation with different thickness. A comparison between deconvoluted images with the amplitudes corrected by the present method and those uncorrected is given to show the effectiveness of the method. The amplitude-crystal thickness dependence for images simulated close to the Scherzer defocus condition has been analysed and the result serves as an empirical basis of the method. The validity and limitation of the method are discussed.

Journal Article↗
PubMed2000

Human neutrophil activation and increased adhesion by various resuscitation fluids.

OBJECTIVE: To determine whether activated neutrophils play a major role in secondary tissue injury after resuscitation in trauma. We hypothesized that human neutrophil activation and adhesion vary, depending on the type and amount of resuscitation fluid used. SETTING: University-based research facility. SUBJECTS: Ten healthy adult volunteers. DESIGN: Whole blood from volunteers was serially diluted in polypropylene tubes with various resuscitation fluids. Fluids tested were phosphate-buffered saline, normal saline, lactated Ringer's solution, dextran, hespan, 5% human albumin, 25% human albumin, 3.5% hypertonic saline, and 7.5% hypertonic saline. Neutrophil activation (intracellular oxidative burst activity with dichlorofluorescin diacetate staining) and adhesion (integrin cell surface expression of CD18) were measured with flow cytometry (fluorescence-activated cell sorting). Blood was diluted with hypertonic saline by controlling for sodium content equal to normal saline. dose-related increase in neutrophil oxidative burst activity as the result of dilution followed with crystalloid fluids and artificial colloids (dextran and hespan). The increase was 12-18 x baseline at the 75% dilution. The increase with 5% human albumin was only 2.2 x baseline, and 25% albumin did not demonstrate any increased intracellular activity. A similar significant increase in the neutrophil adhesion expression (CD18) occurred with artificial colloids (p<.05) and, to a lesser extent, with crystalloids, but not with albumin. Hypertonic saline caused a decrease in CD18 cell surface expression. CONCLUSIONS: This study suggests that the neutrophil activation and adhesion may vary, depending on the type of resuscitative fluid used. All artificial resuscitative fluids may not be similar or innocuous, as demonstrated by the dose-related increase in neutrophil activation and adhesion.

Adult↗
PubMed2000

A method for individual identification of echolocation signals in free-ranging finless porpoises carrying data loggers.

Echolocation click events of a free-ranging juvenile and an adult finless porpoise (Neophocaena phocaenoides) were recorded with an acoustic data logger. Additionally, dive depth and swim speed of the juvenile were recorded with a behavior data logger. Echoes of echolocation signals from the water surface were clearly detected in shallow dives approximately less than 2 m. The delay time between a surface echo and a direct signal corresponded with the two-way transmission time for the animal's depth, indicating that the signals originated from the animal wearing the data loggers. The finless porpoises produced echolocation signals frequently and were thought to be able to detect their depth by listening to echoes from the water surface.

Animals↗