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Biomedical subjects

Jun Wang

Publications and source records attributed to Jun Wang.

612 records · Page 34Linked to original sources
PubMed2002

[Stabilising porous silicon luminescence by a novel titanium-doped stain etching approach].

Porous silicon (PS) with good luminescent stability and homogeneity was fabricated by using a novel titanium-doped stain etching approach. The blue shift and degrading of the photoluminescence (PL) were not observed when stored and annealed in ambient air. The good luminescent stability is attributed to the surface passivation of the PS by both oxygen and titanium during fabrication. The PL position is independent of the etching time. The results indicate that the photon excitation process meets the quantum confinement mechanism since the PL intensity reaches its maximum when the particle size-dependent band gap is in resonance with the exciting photon energy. The photon emission process is, however, not a direct band-band transition, rather through a surface state within the band gap, instead.

Coloring Agents↗
PubMed2002

[Assess respiratory drive by esophageal pressure measurement].

OBJECTIVE: To evaluate the difference between the classificatory results of esophagus pressure monitor and thorax and abdomen belt. METHODS: From Nov. 2000 to Jan. 2001, 34 patients received polysomnographic examination in Beijing Tongren Hospital. The aero digestive pressure was monitored simultaneously at 4 different points, i.e., the distal part of esophagus, hypopharynx, oropharynx and nasopharynx. Respiratory events were classified based on measurement of thorax and abdomen movements and esophageal pressure, and two classification results were compared. RESULTS: Four patients were excluded from comparing classification results because of apnea hypopnea index < 5, or deformity in face and low sleep efficiency. Other 30 patients, 26 men and 4 women, at age of 45.4 +/- 9.5 (30-66), were enrolled. Classificatory difference was found in 9.7% (1,183 out of 12,238) of the respiratory events between two methods. The largest part of apneas reclassified by esophageal pressure measurement were mixed apneas reclassified as obstructive apnea (600). The difference of respiratory drive restore time measured by two methods was found between mixed reclassified obstructive apneas and mixed apneas confirmed by two methods, P = 0.028. No difference between mixed reclassified obstructive apneas and obstructive apneas confirmed by two methods. Difference of apnea classifications was due to the changes of respiratory drive restore time caused by different sensitivity of respiratory drive measurement. The number of difference was related to sensitivity of thorax and abdominal channel (P = 0.000, r2 = 0.653). CONCLUSION: Apneas are easy to be misclassified due to the low sensitivity of thoracic and abdominal channel, and this problem can be solved by using esophageal pressure measurement. All kinds of apneas have anatomic and neuro-muscular factor in common.

Adult↗
PubMed2002

[Juvenile periodontitis survey in 9548 middle school students at Huangpu District in Shanghai].

OBJECTIVE: 9548 middle school students from 11-19 age at Huangpu District in Shanghai were investigated to study the prevalence of juvenile periodontitis(JP). The purpose of the present study was to discover JP at early stage and make correct diagnosis, so the patients can be treated on time. METHODS: From January 2001 to April 2001, debris index(DI), calculus index(CI), sulcus bleeding index(SBI) and community periodontal index for treatment needs (CPITN) were examined in each student. RESULTS: In 9548 investigated (4739 males and 4809 females), prevalence of JP was 0.76%, the ratio of males to females was 1:1.03 (P<0.05). With aging, the detectable rate of gingival bleeding and calculus was increasing, the prevalence of JP was also increasing. CONCLUSION: Since the new classification system of periodontal disease was established, the above cases are worth reevaluating. We should also enhance oral hygiene of the young people.

English Abstract↗
PubMed2002

[Application of endoscopic telescope in the treatment of the juvenile onset recurrent respiratory papillomatosis].

OBJECTIVE: To evaluate the treatment methods of the juvenile onset recurrent respiratory papillomatosis. METHOD: Twelve patients with juvenile onset recurrent respiratory papillomatosis were treated from 1995 to 1999 by using endoscopy. RESULT: Among the 12 cases, 3 cases had no recurrence within one year follow-up and were decannulated,the other 9 cases had recurrence postoperatively, but the recurrence period got longer. CONCLUSION: It is demonstrated that endoscopic surgery is an ideal therapy for the treatment of juvenile onset recurrent respiratory papillomatosis.

Bronchial Neoplasms↗
PubMed2001

[Effect of Autologous or Allogeneic Anti-CD3 Monoclonal Antibody Activated Killer Cells on Normal Hematopoietic Cells]

In order to investigate the effect of autologous and allogeneic anti-CD3 McAb activated killer cells (CD3AK) on normal hematopoietic cells, the immobilized anti-CD3 McAb and low concentration IL-2 were used to activate CD3AK. Flow cytometry was used to assay the phenotype change of CD3AK to analyze the proportional change of CD34(+) cells in normal bone marrow mononuclear cells (BMMNC) cocultured with autologous or allogeneic CD3AK. The effect of CD3AK on normal hematopoietic progenitor cells was also assayed by methylcellulose clonogenic culture of CFU-GM. It was found that 3 - 5 micro g/ml immobilized anti-CD3 McAb and 100 U/ml IL-2 could activate CD3AK effectively. There were 99.51% CD3(+) cells in CD3AK groups. When BMMNCs from healthy volunteers were cocultured with allogeneic CD3AK for six hours, the percentage of CD34(+) cells was decreased 32.37%. CD3AK had no significant influence on autologous BMMNC. Allogeneic and autologous CD3AK were cultured with BMMNC from healthy volunteers for six hours, and then CFU-GM was evaluated. Allogeneic CD3AK inhibited 20.44% CFU-GM formation, but autologous CD3AK had no inhibition on CFU-GM. It is concluded that CD3AK has no inhibition to autologous normal hematopoietic progenitor cells after cocultured with them from these results, while allogeneic CD3AK inhibits the normal hematopoietic progenitor cells significantly.

Journal Article↗
PubMed1998

A multilayer recurrent neural network for solving continuous-time algebraic Riccati equations.

A multilayer recurrent neural network is proposed for solving continuous-time algebraic matrix Riccati equations in real time. The proposed recurrent neural network consists of four bidirectionally connected layers. Each layer consists of an array of neurons. The proposed recurrent neural network is shown to be capable of solving algebraic Riccati equations and synthesizing linear-quadratic control systems in real time. Analytical results on stability of the recurrent neural network and solvability of algebraic Riccati equations by use of the recurrent neural network are discussed. The operating characteristics of the recurrent neural network are also demonstrated through three illustrative examples.

Journal Article↗
PubMedDate not supplied

Study on the effect of thiamine on the metabolism of yeast by intrinsic fluorescence.

Thiamine in living human bodies exists mainly as diphosphate, which works as a co-enzyme of the sugar metabolism system (active vitamin B1). Thiamine deficiency brings many clinically significant problems, such as dysphoria, quadriplegia and dyspepsia. Intrinsic fluorescence has an advantage over the extrinsic fluorescence of an unperturbed environment during investigation, especially in complex systems such as biological cells and tissues. Cellular fluorescence provides a sensitive index of the functional state of a living cell (1). Different amounts of thiamine were added to culture medium and the fluorescence of tryptophan and NADH from yeast was determined. When the thiamine concentration was greater than 0-0.16 microg/mL, the intensity of tryptophan fluorescence increased linearly, whereas the NADH fluorescence decreased. When the thiamine concentration was above 0.24 microg/mL, the fluorescence of tryptophan and NADH was almost unchanged. We concluded that low thiamine concentration in culture medium had a large effect on the growth of Saccharomyces cerevisiae and possible reasons are discussed.

Cell Proliferation↗
PubMedDate not supplied

Water-soluble and nonionic polyphosphoester: synthesis, degradation, biocompatibility and enhancement of gene expression in mouse muscle.

A nonionic and water-soluble polyphosphoester, poly(2-hydroxyethyl propylene phosphate) (PPE3), was synthesized by chlorination of poly(4-methyl-2-oxo-2-hydro-1,3,2-dioxaphospholane), followed by esterification with 2-benzyloxyethanol and deprotection of the hydroxyl group by catalytic hydrogenation in the presence of Pd-C. PPE3 degraded rapidly in PBS 7.4 at 37 degrees C. The cytotoxicity and tissue compatibility assays suggested good biocompatibility of PPE3 in vitro and in vivo. The expression of pVR1255 Luc plasmid in mouse muscle after intramuscular (i.m.) injection of DNA formulated with PPE3 solution in saline was enhanced up to 4-fold compared with that of naked DNA. These results suggest the potential of this polyphosphoester for naked DNA-based gene therapy. The advantages of this polymer design include the biodegradability of the polyphosphoester and its structural versatility, which allows the fine-tuning of the physicochemical properties to optimize the enhancement of gene expression in muscle.

Animals↗
PubMedDate not supplied

Ternary complexes comprising polyphosphoramidate gene carriers with different types of charge groups improve transfection efficiency.

To understand the influence of charge groups on transfection mediated by polymer complexes, we have synthesized a series of biodegradable and cationic polyphosphoramidates (PPAs) with an identical backbone but different side chains. Our previous study showed that PPA with a spermidine side chain (PPA-SP) showed high transfection efficiency in culture, whereas PPAs with secondary, tertiary, and quaternary amino groups were significantly less efficient. To investigate whether the coexistence of 1 degrees amino charge groups with 3 degrees and 2 degrees amino charge groups in the DNA/polymer complexes would enhance their transfection efficiency, we evaluated a ternary complex system containing DNA and PPAs with 1 degrees amino groups (PPA-SP) and 3 degrees amino groups (PPA-DMA) and a quaternary complex system containing DNA and PPAs with 1 degrees and 2 degrees and 3 degrees amino groups (PPA-EA/PPA-MEA/PPA-DMA), respectively. Ternary complexes mediated 20 and 160 times higher transfection efficiency in COS-7 cells than complexes of DNA with PPA-SP or PPA-DMA alone, respectively. Similarly, quaternary complexes exhibited 8-fold higher transfection efficiency than PPA-EA/DNA complexes. The mechanism of enhancement in transfection efficiency by the mixture carriers appears to be unrelated to the particle size, zeta potential, or DNA uptake. The titration characterization and the transfection experiments using a proton pump inhibitor suggest that the enhancement effect is unlikely due to the slightly improved buffering capacity of the mixture over PPA-SP. This approach represents a simple strategy of developing polymeric gene carriers and understanding the mechanisms of polymer-mediated gene transfer.

Amides↗
PubMedDate not supplied

Multiphoton excited fabrication of collagen matrixes cross-linked by a modified benzophenone dimer: bioactivity and enzymatic degradation.

Multiphoton excited (MPE) photochemistry is used to fabricate model tissue engineering scaffolds directly from types I, II, and IV collagen. A modified benzophenone dimer (BPD) provides the photoactivation and becomes incorporated into the resulting collagen matrixes. Unlike xanthene photochemistries, the benzophenone dimer can be used in acidic environments, where most forms of collagen have the greatest solubility. The minimum feature sizes are investigated by using two- and three-photon excitation, where the latter provides for superior "resolution" and suggests that collagen structures can be fabricated on the size scales of focal contacts. The resulting structures display excellent retention of bioactivity as evidenced by highly specific cell adhesion as well as immunofluorescence labeling. Structural and chemical aspects of the collagen matrixes are probed through measuring the enzymatic degradation through specific and nonspecific proteases, as the resulting relative rates are consistent with the activity of these enzymes. The degradation rates can also be controlled through varying the cross-link density in the matrixes, which is achieved through tuning the exposure dose during the fabrication process. The degradation rates are also found to be consistent with swelling/shrinking measurements and thus the average mesh size of the matrixes. In all cases the enzymatic degradations are well-fit single exponentials, suggesting that the matrixes can be fabricated with a priori knowledge of their structural properties. These results coupled with the resulting bioactivity suggest that the multiphoton fabrication process may be a powerful tool for the creation of cell-sized tissue engineering scaffolds.

Benzophenones↗
PubMedDate not supplied

One-step, painting-like coating procedures to make surfaces highly and permanently bactericidal.

Previously we found that covalent attachment of long-chained, moderately hydrophobic polycations to surfaces of solid objects renders the latter permanently bactericidal. Herein we replaced such surface-specific, multistep immobilization techniques with a single-step, general procedure akin to common painting. Glass or polyethylene slides were briefly dipped into organic solutions of certain optimally hydrophobic N-alkyl-PEI (where PEI stands for branched 750-kDa polyethylenimine) polycations, followed by solvent evaporation. The resultant polycation-coated slides were able to kill on contact all of the encountered bacterial cells, whether the Gram-positive human pathogen Staphylococcus aureus or its Gram-negative brethren Escherichia coli. This biocidal effect was found not to be caused by N-alkyl-PEI molecules leached from the surface. Further examination of the mechanism of this bactericidal action suggested that the surface-deposited N-alkyl-PEI kills bacteria by rupturing their cellular membranes. This conclusion was further supported by studies in which the molecular weight of PEI and the hydrophobicity of the alkyl moiety were varied.

Escherichia coli↗
PubMedDate not supplied

Characteristic sequences for DNA primary sequence.

A DNA sequence can be identified with a word over an alphabet N = [A, C, G, T]. Characteristic sequences of a DNA sequence are given in term of classifications of bases of nucleic acids. Using the characteristic sequences, we construct a set of 2 x 2 matrices to represent DNA primary sequences, which are based on counting of the frequency of occurrence of all (0,1) triplets of characteristic sequences. Furthermore, the leading eigenvalues of these matrices are computed and considered as invariants for the DNA primary sequences. Similarity and dissimilarity analysis based on the characteristic sequences are given for eight exon-1 genes of beta-globin about eight species.

Animals↗
PubMedDate not supplied

New invariant of DNA sequences.

For a DNA sequence with n bases, one can always associate it with an n x n nonnegative real symmetric matrix whose diagonal entries are zero. Once the matrix is given, its leading eigenvalue is usually calculated and used as an invariant to characterize the DNA sequence. Let M be such a matrix, and lambda1 its leading eigenvalue. Then (1/n)//M//m1 and sqrt [(n-1)/n]//M//F are the lower and upper bounds of lambda1, respectively. Since their arithmetic average is an approximate value of lambda1 and simpler for calculation, we can use it as an alternative invariant to characterize the DNA sequence. The utility of the new parameter is illustrated on the DNA sequences of five species: human, chimpanzee, mouse, rat, and gallus.

Animals↗
PubMedDate not supplied

Advances in the mechanisms of cell delivery to cardiovascular scaffolds: comparison of two rotating cell culture systems.

Having a reliable method of delivering cells to polymer scaffolds in vitro is fundamental to the development of tissue engineered structures. This paper compares the efficacy of two rotating systems for this purpose. Ten conduits, measuring 40 mm by 10 mm, were fabricated from polyglycolic acid mesh and poly-4-hydrobutyrate. Five conduits were placed in a rotating wall vessel (RWV, Synthecon Inc., Houston, TX), developed by the National Aeronautics and Space Administration (NASA); five conduits were also placed in rotating individual sealed tubes (RISTs). Medium in the RWV was left unchanged for the duration of the experiment; medium in the RISTs required daily change. Samples of the discarded medium and samples from the RWV were analyzed for pH, pCO2, pO2, and lactate concentration. Constructs were assayed for DNA content as a surrogate for cell number. In the RWV, pH, pCO2, and pO2 remained stable, while the lactate concentration gradually increased. The measure of PO2 did not differ significantly between the RWV and the RISTs, but the pH was lower and the pCO2 and the lactate concentration measurements were higher in the RIST system at each time point (p = 0.001). After 6 days (p = 0.001), the total DNA per conduit was 226+/-7 microg for the conduits seeded in the RISTs and 396+/-18 microg for the conduits in the RWV, suggesting that the RWV is superior to the RIST system for delivering cells to polymer scaffolds.

Animals↗
PubMedDate not supplied

GDNF acutely potentiates Ca2+ channels and excitatory synaptic transmission in midbrain dopaminergic neurons.

Glial cell line-derived neurotrophic factor (GDNF) is best known for its long-term survival effect on dopaminergic neurons in the ventral midbrain. A recent study showed that acute application of GDNF to these neurons suppresses A-type potassium channels and potentiates neuronal excitability. Here we have characterized the acute effects of GDNF on Ca(2+) channels and synaptic transmission. GDNF rapidly and reversibly potentiated the high voltage-activated (HVA) Ca(2+) channel currents in cultured dopaminergic neurons. Analyses of channel kinetics indicate that GDNF decreased the activation time constant, increased the inactivation and deactivation time constants of HVA Ca(2+) channel currents. Ca(2+) imaging experiments demonstrate that GDNF facilitated Ca(2+) influx induced by membrane depolarization. To investigate the physiological consequences of the Ca(2+) channel modulation, we examined the acute effects of GDNF on excitatory synaptic transmission at synapses made by these dopaminergic neurons, which co-release the transmitter glutamate. Within 3 min of application, GDNF increased the amplitude of spontaneous and evoked excitatory autaptic- or multiple-postsynaptic currents. The frequency as well as the amplitude of miniature excitatory postsynaptic currents was also increased. These results reveal, for the first time, an acute effect of GDNF on synaptic transmission and its potential mechanisms, and suggest that an important function of GDNF for midbrain dopaminergic neurons is the acute modulation of transmission and ion channels.

Animals↗
PubMedDate not supplied

Interwoven dendritic processes of follicular dendritic cell sarcoma demonstrated on ultrafast papanicolaou-stained smears: a case report.

BACKGROUND: Follicular dendritic cell (FDC) tumor is a rare tumor derived from accessory cells in the lymphoid follicles. FDC tumors are typically diagnosed on histology based on immunoreactivity to at least 1 of the FDC markers (CD21, CD23 or CD35) or based on the characteristic ultrastructural feature of long, interwoven, cytoplasmic, dendritic processes connected by desmosomes. CASE: We observed novel cytologic features of FDC sarcoma in a liver fine needle aspirate of a 46-year-old man status post surgery and chemotherapy for FDC sarcoma, originating in the gastrointestinal tract with metastases to the liver, pancreas and spleen. In the Diff-Quik- and Papanicolaou-stained smears, the tumor cells presented in syncytial fragments as well as single cells, as previously reported in the cytologic literature. However, the single cells were interconnected to neighboring single cells via long, thin, threadlike cytoplasmic processes in ultrafast Papanicolaou (UFP)-stained smears. The tumor cells possessed multipolar cytoplasmic processes rather than unipolar ones, as previously reported. CONCLUSION: The ultrastructural features of a web of interwoven, dendritic, cytoplasmic processes of FDC tumor was demonstrated for the first time on cytology. Observation of this feature may allow the diagnosis to be made on cytology prior to histology, immunohistochemistry or electron microscopy.

Antigens, Surface↗
PubMedDate not supplied

Association of umbilical placental vascular disease with fetal acute inflammatory cytokine responses.

OBJECTIVE: We examined the hypothesis that fetal proinflammatory cytokine release is a feature of placental vascular disease causing fetal compromise. We measured the concentrations of fetal proinflammatory cytokines interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and interleukin-8 (IL-8) in the presence of vascular disease in the umbilical placental villous circulation. Vascular disease was identified by high-resistance umbilical artery Doppler flow velocity waveform studies. METHODS: We measured levels of the inflammatory cytokines IL-6 and TNF-alpha and the chemokine IL-8 in fetal blood. Blood was collected from the umbilical vein at delivery, and serum was stored at -70C until assayed using chemiluminescent and enzyme-linked immunosorbent assay methods. We studied 36 normal pregnancies delivered by elective cesarean at term and 50 pregnancies with a high-resistance umbilical artery Doppler flow velocity waveform pattern indicative of fetal placental vascular disease delivered by elective cesarean because of potential fetal compromise. RESULTS: In the presence of umbilical placental vascular disease there were significantly higher levels of IL-6 (median 5.3 pg/mL, P <.05) and IL-8 (median 26.5 pg/mL, P <.01) compared with normal pregnancies (median value of IL-6 and IL-8 were below assay threshold). There was no difference for TNF-alpha, with the median results undetectable in both groups. CONCLUSION: We found higher concentrations of IL-6 and IL-8 in the fetal circulation in the presence of umbilical placental vascular disease.

Adult↗