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Biomedical subjects

H L Wang

Publications and source records attributed to H L Wang.

At least 73 records · Page 4Linked to original sources
PubMed2000

[Effects of noise and music on EEG power spectrum].

Objective. To observe the effect of noise and music on EEG power spectrum. Method. 12 healthy male pilots aged 30 +/- 0.58 years served as the subjects. Dynamic EEG from 16 regions was recorded during quiet, under noise or when listening to music using Oxford MR95 Holter recorder. Changes of EEG power spectrum of delta, theta, alpha1, alpha2, beta1 and beta2, frequency components in 16 regions were analyzed. Result. The total alpha1 power was significantly decreased, while the total theta power was significantly increased when listening to music; It implies that the interhemispheric transmission of information in the frontotemporal areas might be involved. Conclusion. The changes of the EEG power spectrum were closely related to man's emotions; relaxation was associated with music; Individual difference exists in the influence of sound on EEG.

Adult↗
PubMed1999

Highly sensitive biological and chemical sensors based on reversible fluorescence quenching in a conjugated polymer.

The fluorescence of a polyanionic conjugated polymer can be quenched by extremely low concentrations of cationic electron acceptors in aqueous solutions. We report a greater than million-fold amplification of the sensitivity to fluorescence quenching compared with corresponding "molecular excited states." Using a combination of steady-state and ultrafast spectroscopy, we have established that the dramatic quenching results from weak complex formation [polymer(-)/quencher(+)], followed by ultrafast electron transfer from excitations on the entire polymer chain to the quencher, with a time constant of 650 fs. Because of the weak complex formation, the quenching can be selectively reversed by using a quencher-recognition diad. We have constructed such a diad and demonstrate that the fluorescence is fully recovered on binding between the recognition site and a specific analyte protein. In both solutions and thin films, this reversible fluorescence quenching provides the basis for a new class of highly sensitive biological and chemical sensors.

Biosensing Techniques↗
PubMed1999

Plant paralog to viral movement protein that potentiates transport of mRNA into the phloem.

CmPP16 from Cucurbita maxima was cloned and the protein was shown to possess properties similar to those of viral movement proteins. CmPP16 messenger RNA (mRNA) is present in phloem tissue, whereas protein appears confined to sieve elements (SE). Microinjection and grafting studies revealed that CmPP16 moves from cell to cell, mediates the transport of sense and antisense RNA, and moves together with its mRNA into the SE of scion tissue. CmPP16 possesses the characteristics that are likely required to mediate RNA delivery into the long-distance translocation stream. Thus, RNA may move within the phloem as a component of a plant information superhighway.

Amino Acid Sequence↗
PubMed1999

Effects of smoking on local delivery of controlled-release doxycycline as compared to scaling and root planing.

This paper examines the effects of smoking on the treatment outcomes of two nonsurgical therapies: (1) scaling and root planing alone (SRP) or (2) controlled-release of subgingivally delivered doxycycline hyclate in a polylactic acid based polymer gel. Subjects from 2 9-month multicenter studies were classified as nonsmokers (never smoked: 100 subjects), former smokers (137 subjects), and current smokers (> or = 10 cigarettes/day: 121 subjects). Clinical parameters were analyzed for treated sites with baseline probing depths > or = 5 mm and for a subset of treated sites with baseline probing depths of > or = 7 mm. Clinical parameters (plaque levels, clinical attachment levels, pocket depths, and bleeding on probing) were analyzed at baseline, 4, 6, and 9 months. In the doxycycline treated group in general, there were neither marked significant differences in clinical attachment gain nor differences in probing depth reduction among the 3 smoking groups. On the other hand, in the scaling and root planing treated group in general, there were significant differences in clinical attachment gain and pocket depth reduction, with non-smokers responding better than former smokers and current smokers at 6 and 9 months. These differences in clinical response between scaling and root planing alone versus controlled-release of locally-delivered doxycycline hyclate among these 3 smoking groups are discussed in relation to treatment implications for smokers.

Administration, Topical↗
PubMed1999

Acetylcholine receptor M3 domain: stereochemical and volume contributions to channel gating.

By defining the functional defect in a congenital myasthenic syndrome (CMS), we show that the third transmembrane domain (M3) of the muscle acetylcholine receptor governs the speed and efficiency of gating of its channel. The clinical phenotype of this CMS results from the mutation V285I in M3 of the alpha subunit, which attenuates endplate currents, accelerates their decay and causes abnormally brief acetylcholine-induced single-channel currents. Kinetic analysis of engineered alpha V285I receptors demonstrated a predominant effect on channel gating, with abnormally slow opening and rapid closing rates. Analysis of site-directed mutations revealed stereochemical and volume-dependent contributions of alpha V285 to channel gating. Thus, we demonstrate a functional role for the M3 domain as a key component of the nicotinic acetylcholine receptor channel-gating mechanism.

Amino Acid Sequence↗
PubMed1999

Tissue factors on acute promyelocytic leukemia and endothelial cells are differently regulated by retinoic acid, arsenic trioxide and chemotherapeutic agents.

The aberrant expression of tissue factor (TF) in acute promyelocytic leukemia (APL) cells has been implicated in the pathogenesis of the APL coagulopathy. In this study, we found that in APL patients receiving ATRA or As2O3 treatment, the improvement in hypercoagulobility and hyperfibrinolysis paralleled the correction of plasma fibrinogen level and amelioration of bleeding symptoms. Notably, clinical improvement was also correlated to ATRA/As2O3-induced rapid decrease of membrane procoagulant activity (PCA) and TF contents of APL blasts. Consistent with the in vivo findings, the membrane PCA, TF antigen and its mRNA level within NB4 cells were rapidly down-regulated by 1 microM ATRA or As2O3, while 0.2 microg/ml DNR increased these TF parameters prior to its effect upon apoptosis induction. The down-regulation of TF mRNA by ATRA was partially de novo protein synthesis-dependent and at least partially attributed to a mechanism of destabilizing TF mRNA. On the other hand, in addition to its modulation on mRNA, As2O3 could also induce an accelerated TF protein turnover. These distinct effects were corroborated with the properties of these agents in causing the degradation of PML-RARalpha protein. All three therapeutic agents, however, enhanced the potential of NB4 cells to stimulate the expression of TF and PCA in endothelium. Taken together, our data suggest that the rapid and distinct regulation of TF on APL cells by these therapeutic agents might at least partially contribute to their effects on APL coagulopathy.

Adolescent↗
PubMed1999

A conserved arginine in the distal third intracellular loop of the mu-opioid receptor is required for G protein activation.

In the present study, the functional significance of the intracellular C-terminal loop of the mu-opioid receptor in activating Gi proteins was determined by constructing a C-terminal deletion mutant mu(C delta 45) receptor, which lacks the carboxyl 45 amino acids. When the truncated mu(C delta 45) receptor was stably expressed in human embryonic kidney (HEK) 293 cells, the efficacy and the potency of [D-Ala2,N-Me-Phe4,Gly-ol5]enkephalin (DAMGO), a specific mu-opioid receptor agonist, to inhibit forskolin-stimulated adenylate cyclase activity were not significantly affected. Similar to other G-coupled receptors, the third cytoplasmic loop of the mu-opioid receptor contains conserved basic residues (R276/R277/R280) at the C-terminal segment. Mutating these basic residues to neutral amino acids (L276/M277/L280) greatly impaired the ability of DAMGO to inhibit forskolin-stimulated cyclic AMP formation. Replacing R276/R277 with L276/M277 did not affect the efficacy and potency by which DAMGO inhibits the adenylate cyclase activity. In HEK 293 cells stably expressing mutant (R280L) mu-opioid receptors, the ability of DAMGO to inhibit forskolin-stimulated cyclic AMP production was greatly reduced. These results suggest that the intracellular carboxyl tail of the mu-opioid receptor does not play a significant role in activating Gi proteins and that the arginine residue (R280) at the distal third cytoplasmic loop is required for Gi activation by the mu-opioid receptor.

Adenylyl Cyclases↗
PubMed1999

Aberrant cutaneous expression of the angiogenic factor midkine is associated with neurofibromatosis type-1.

Neurofibromatosis type 1 is a common autosomal dominant disorder (incidence 1:3500) characterized by lesions that include neural crest derivatives such as Schwann cells and melanocytes. A critical event in the pathogenesis of neurofibromatosis type 1 is the heterozygous germ-line loss of the tumor suppressor gene NF1. Additional genetic and/or epigenetic events have been posited, including various alterations in growth factor expression. By in situ hybridization and immunohistochemistry, we demonstrate aberrant expression of the angiogenic and tumorigenic growth factor midkine in the skin of patients with neurofibromatosis type 1, but not normal individuals. We demonstrate that midkine expression is independent of the presence of neurofibromas, and thus appears to be associated with mutations in the NF1 gene. Furthermore, midkine-containing culture media is shown to stimulate the growth of human endothelial and neurofibroma-derived cells. In conclusion, we introduce the skin as a source of dysregulated growth factors in neurofibromatosis type 1, and suggest the further study of the angiogenic factor midkine in neurofibromatosis type 1 pathogenesis.

Angiogenesis Inducing Agents↗
PubMed1999

Two multi-center studies evaluating locally delivered doxycycline hyclate, placebo control, oral hygiene, and scaling and root planing in the treatment of periodontitis.

BACKGROUND: The clinical efficacy and safety of doxycycline hyclate (8.5% w/w) delivered subgingivally in a biodegradable polymer (DH) was compared to placebo control (VC), oral hygiene (OH), and scaling and root planing (SRP) in 2 multi-center studies. METHODS: Each study entered 411 patients who demonstrated moderate to severe periodontitis. Patients had 2 or more quadrants each with a minimum of 4 qualifying pockets > or =5 mm that bled on probing. At least 2 of the pockets were > or =7 mm. Treatment with DH, VC, OH, or SRP was provided at baseline and again at month 4. Clinical parameters were recorded monthly. RESULTS: DH and SRP resulted in nearly identical clinical changes over time in both studies. Mean 9 month clinical attachment level gain (ALG) was 0.8 mm for the DH group and 0.7 mm for the SRP group in Study 1, and 0.8 mm (DH) and 0.9 mm (SRP) in Study 2. Mean probing depth (PD) reduction was 1.1 mm for the DH group and 0.9 mm for the SRP group in Study 1 and 1.3 mm for both groups in Study 2. Frequency distributions showed an ALG > or =2 mm in 29% of DH sites versus 27% of SRP sites in Study 1 and 31% of DH sites versus 34% of SRP sites in Study 2. PD reductions > or =2 mm were seen in 32% of DH sites versus 31% of SRP sites in Study 1 and 41% of DH sites versus 43% of SRP sites in Study 2. Comparisons between DH, VC, and OH treatment groups showed DH treatment to be statistically superior to VC and OH. Safety data demonstrated a benign safety profile with use of the DH product. CONCLUSIONS: Results of this trial demonstrate that treatment of periodontitis with subgingivally delivered doxycycline in a biodegradable polymer is equally effective as scaling and root planing and superior in effect to placebo control and oral hygiene in reducing the clinical signs of adult periodontitis over a 9-month period. This represents positive changes resulting from the use of subgingivally applied doxycycline as scaling and root planing was not limited regarding time of the procedure or use of local anesthesia.

Absorbable Implants↗
PubMed1999

The use of biodegradable polylactic acid barrier materials in the treatment of grade II periodontal furcation defects in humans--Part II: A multicenter investigative surgical study.

This study evaluated whether differences in design of 3-dimensional polylactic acid barriers (EPi-Guide and Guidor) would influence hard tissue results in the treatment of Grade II furcations in humans. A multicenter study was conducted, using 40 patients with moderate to advanced bilateral chronic adult periodontitis of the mandibular first or second molars. After flap access, debridement, and root preparation, surgical bone level measurements were taken and membranes were placed on a random basis. Surgical reentry occurred at 1 year. Data collected from all 3 investigative centers were pooled and analyzed using an analysis of variance appropriate for a counterbalancing design. Both barrier materials resulted in significant gains of attachment level and defect reduction. The composite reduction in the vertical component of the osseous defects was greater in the sites treated with Epi-Guide as compared to those treated with Guidor; the difference between barriers reached statistical significance (P = 0.02).

Absorbable Implants↗
PubMed1999

Synthesis and methyltransferase activity of nonstructural protein nsP1 in Sindbis virus-infected Aedes albopictus cells.

To investigate the synthesis and turnover of the nonstructure protein, nsP1, in Aedes albopictus cells, we labeled infected cells with [35S]-methionine and immunoprecipitated nsP1 with a polyclonal monospecific rabbit antibody. Synthesis of nsP1 in mosquito cells could be detected 2 hr after infection and continued as long as 24 hr post-infection, regardless whether the infected cells were maintained at 28 degrees C , 34.5 degrees C , or 37 degrees C. Whereas the time pattern of nsP1 synthesis varied with temperature. Nonstructural protein 1 synthesis at 28 degrees C was maximal at 4 hr, then decreased. At 37 degrees C synthesis reached a high level at 2 hr and remained constant for 24 hr. Pulse-chase experiments showed that nsP1 in mosquito cells, whether made as early as 5 hr post-infection or as late as 24 hr, were stable during that time, the longest period tested. Enzyme activity reached a maximum at 10 hr and remained almost the same level until 24 hr. The yield of Sindbis virus from mosquito cells was higher at 34.5 degrees C and 37 degrees C than at 28 degrees C. Methyltransferase activity was needed for modification of positive-strand genomic and subgenomic RNAs. The activity of methyltransferase observed until late in the replication cycle probably accounted for both the continued synthesis and minimal turnover of nsP1.

Aedes↗
PubMed1998

Expression of integrin-associated protein gene associated with memory formation in rats.

The present study has adopted the PCR differential display method to identify cDNA clones associated with memory formation in rats. The one-way inhibitory avoidance learning task was used as the behavioral paradigm. Total RNA isolated from the hippocampus of poor-memory (<80 sec) and good-memory (600 sec) rats 3 hr after training was used for comparison. Three cDNA fragments corresponding to different spliced forms of integrin-associated protein (IAP) mRNA were found to be differentially expressed in the hippocampus of good-memory rats. Quantitative reverse transcription-PCR revealed approximately four fold higher of IAP mRNA level in good-memory rats. This result was confirmed further by in situ hybridization analysis, and the major difference was in the dentate gyrus. It has been demonstrated that this difference in IAP mRNA expression is not attributable to different sensitivities of individual rats to electric shock. Rapid amplification of cDNA ends obtained the full-length IAP cDNA, which is 1192 bp in length excluding the poly(A+) tail. The IAP mRNA expression was significantly upregulated by NMDA and amphetamine injections to the dentate gyrus of the hippocampus. On the other hand, injection of antisense oligonucleotide complementary to the IAP transcript markedly impaired memory retention in rats and decreased the amplitude and slope of EPSP in the in vivo long-term potentiation paradigm. These results together suggest that IAP gene expression plays an important role in memory formation and synaptic plasticity in rat hippocampus.

Amphetamine↗
PubMed1998

Mutations in viral movement protein alter systemic infection and identify an intercellular barrier to entry into the phloem long-distance transport system.

Viral systemic infection of a plant host involves two processes, cell-to-cell movement and long-distance transport. Molecular determinants associated with these two processes were probed by investigating the effects that alanine scanning mutations in the movement protein (MP) of red clover necrotic mosaic virus (RCNMV) had on viral infection in the plant hosts Nicotiana edwardsonii, Vigna unguiculata (cowpea), and the experimental plant Nicotiana benthamiana. Plants were inoculated with RCNMV expressing wild-type and mutant forms of the MP. Immunocytochemical studies at the light and electron microscope levels were performed on these plants, using a polyclonal antibody raised against the RCNMV capsid protein to identify the cells/tissues that RCNMV could infect. These experiments demonstrated that one cellular boundary at which the RCNMV MP functions to facilitate entry into the phloem long-distance transport system is located at the interfaces between the bundle sheath and phloem parenchyma cells and the companion cell-sieve element complex. Interestingly, in Nicotiana tabacum, a host that only allows a local infection, RCNMV cell-to-cell movement was found to be blocked at this same intercellular boundary. Four mutants that were able to systemically infect N. benthamiana were partially or completely defective for systemic infection of N. edwardsonii and cowpea, which indicated that these MP mutants exhibited host-specific defects. Thus, the roles of the RCNMV MP in cell-to-cell movement and in long-distance transport appear to be genetically distinct. These results are discussed in terms of the mechanism by which RCN MV enters the phloem to establish a systemic infection.

Biological Transport↗
PubMed1998

Brain-derived neurotrophic factor antisense oligonucleotide impairs memory retention and inhibits long-term potentiation in rats.

We have examined the relationship between brain-derived neurotrophic factor gene expression in the hippocampus and memory retention as well as long-term potentiation of rats. One-way inhibitory avoidance learning was adopted as the behavioural paradigm. Results revealed that brain-derived neurotrophic factor messenger RNA levels in the dentate gyrus of the hippocampus were markedly increased at 1 h, 3 h and 6 h post-training in rats showing good retention performance when compared with the poor retention controls. Direct injection of brain-derived neurotrophic factor antisense oligonucleotide into the dentate gyrus of the hippocampus before memory consolidation takes place markedly impaired retention performance in rats. It also significantly decreased brain-derived neurotrophic factor messenger RNA level in the dentate gyrus. The same antisense treatment also markedly reduced the amplitude and slope of excitatory postsynaptic potential as well as the brain-derived neurotrophic factor messenger RNA level in the dentate gyrus. These results suggest that hippocampal brain-derived neurotrophic factor gene expression plays an important role in the memory consolidation process and in the expression of long-term potentiation in rats. These results provide the first evidence to relate brain-derived neurotrophic factor gene expression and memory function in vertebrates. It further suggests that brain-derived neurotrophic factor gene expression is involved in behavioural plasticity.

Animals↗
PubMed1998

Mode switching kinetics produced by a naturally occurring mutation in the cytoplasmic loop of the human acetylcholine receptor epsilon subunit.

We describe the genetic and kinetic defects in a congenital myasthenic syndrome caused by heteroallelic mutations of the acetylcholine receptor (AChR) epsilon subunit gene. The mutations are an in-frame duplication of six residues in the long cytoplasmic loop (epsilon1254ins18) and a cysteine-loop null mutation (epsilonC128S). The epsilon1254 ins18 mutation causes mode switching in the kinetics of receptor activation in which three modes activate slowly and inactivate rapidly. The epsilon1245ins18-AChR at the endplate shows abnormally brief activation episodes during steady state agonist application and appears electrically silent during the synaptic response to acetylcholine. The phenotypic consequences are endplate AChR deficiency, simplification of the postsynaptic region, and compensatory expression of fetal AChR that restores electrical activity at the endplate and rescues the phenotype.

Acetylcholine↗
PubMed1998

Corticotrophin-releasing factor produces a long-lasting enhancement of synaptic efficacy in the hippocampus.

We have previously demonstrated that intra-hippocampal injection of corticotrophin-releasing factor improved memory retention of an inhibitory avoidance learning in rats; while the electrophysiological effects corticotrophin-releasing factor produces on hippocampal neurons are largely uncharacterized. In the present study, we found that corticotrophin-releasing factor injected into the dentate gyrus of hippocampus produced a dose-dependent and long-lasting enhancement in synaptic efficacy of these neurons, as measured by an increase in the amplitude and slope of population excitatory postsynaptic potentials, as well as the amplitude of population spike. The onset of corticotrophin-releasing factor-induced potentiation was slow. It was observed approximately 40-60 min after corticotrophin-releasing factor administration and lasted for more than 5 h. This effect of corticotrophin-releasing factor was blocked by pretreatment with the cyclase-adenosine-3,5-monophosphate (cAMP) inhibitor Rp-adenosine-3,5-cyclic monophosphothiolate triethylamine (Rp-cAMPS) and partially blocked by the N-methyl-D-aspartate receptor antagonist MK-801. Further, pretreatment with corticotrophin-releasing factor receptor antagonist dose-dependently diminished tetanization-induced long-term potentiation, and corticotrophin-releasing factor and tetanic stimuli had an additive effect on hippocampal neuron excitation. Moreover, direct injection of corticotrophin-releasing factor increased cAMP level in the dentate gyrus. These results together suggest that corticotrophin-releasing factor-induced potentiation simulates the late phase of tetanization-induced long-term potentiation and cAMP seems to be the messenger mediating this effect. Moreover, corticotrophin-releasing factor-induced potentiation and long-term potentiation may share some similar mechanisms, and corticotrophin-releasing factor is probably involved in the neural circuits underlying long-term potentiation. Thus, corticotrophin-releasing factor may play an important role in modulating synaptic plasticity in the hippocampus.

Action Potentials↗
PubMed1998

Functional modulation of P2X2 receptors by cyclic AMP-dependent protein kinase.

It is generally believed that protein phosphorylation is an important mechanism through which the functions of voltage- and ligand-gated channels are modulated. The intracellular carboxyl terminus of P2X2 receptor contains several consensus phosphorylation sites for cyclic AMP (cAMP)-dependent protein kinase (PKA) and protein kinase C (PKC), suggesting that the function of the P2X2 purinoceptor could be regulated by the protein phosphorylation. Whole-cell voltage-clamp recording was used to record ATP-evoked cationic currents from human embryonic kidney (HEK) 293 cells stably transfected with the cDNA encoding the rat P2X2 receptor. Dialyzing HEK 293 cells with phorbol 12-myristate 13-acetate, a PKC activator, failed to affect the amplitude and kinetics of the ATP-induced cationic current. The role of PKA phosphorylation in modulating the function of the P2X2 receptor was investigated by internally perfusing HEK 293 cells with 8-bromo-cAMP or the purified catalytic subunit of PKA. Both 8-bromo-cAMP and PKA catalytic subunit caused a reduction in the magnitude of the ATP-activated current without affecting the inactivation kinetics and the value of reversal potential. Site-directed mutagenesis was also performed to replace the intracellular PKA consensus phosphorylation site (Ser431) with a cysteine residue. In HEK 293 cells expressing (S431C) mutant P2X2 receptors, intracellular perfusion of 8-bromo-cAMP or purified PKA catalytic subunit did not affect the amplitude of the ATP-evoked current. These results suggest that as with other ligand-gated ion channels, protein phosphorylation by PKA could play an important role in regulating the function of the P2X2 receptor and ATP-mediated physiological effects in the nervous system.

Animals↗