Biomedical subjects

N Wang

Publications and source records attributed to N Wang.

At least 181 records · Page 10Linked to original sources

PubMed1999

[Comparison of results of chamber angle examination by ultrasound biomicroscopy and gonioscopy].

OBJECTIVE: To compare the consistency of the chamber angles examined by ultrasound biomicroscope (UBM) and gonioscope and provide gonioscopic examination with new methods and technology. METHODS: 10 patients (20 eyes) were selected for the research. The same eyes were examined by UBM and gonioscope in turns. The results from the two methods were compared and the data were analyzed with Spearman correlation test. RESULTS: The results of two methods of chamber angle examination were well consistent when the angle was wide, but the consistency was not good when it was narrow. The angle examined by a gonioscope was wider than that by UBM. When the iris root insertion was evaluated in a narrow angle, the consistency was also not good, and when the peripheral iris morphology was evaluated, there were almost inconsistent results in one-fourth of the patients. CONCLUSIONS: The results of chamber angle examined by a gonioscope show a little wider than its natural status. Especially, it is difficult to distinguish the functional closure from the adhesive closure. Under the influence of light, the determination of iris root insertion by a gonioscope has a sense of conjecture. When peripheral iris morphology is evaluated, the influence of irregular iris might result in a wrong conclusion. Therefore, the technique of gonioscopic examination should be improved.

Adult↗

PubMed1999

[Nucleotide sequence analysis for high variance region of hepatitis C virus in patients with hemodialysis].

OBJECTIVE: To investigate the route of transmission for hepatitis C virus (HCV) infection in patients on hemodialysis (HD). METHODS: Nucleotide sequence of high variance region (HVR) of HCV was analyzed with nucleotide sequencing technique in 15 HD patients, and its homology was compared. RESULTS: Comparison of the nucleotide sequences of HCV HVR in 15 HD patients showed that their homologies in isolates 8, 12 and 14 reached 97.50%, 95.00% in isolates 4, 5 and 10, and more than 80.00% in isolates 1, 3 - 8 and 10 - 14. Clinical data showed that all these patients were hemodialyzed in the same room with the same HD machine. Isolates 2 and all others were 61.25% - 66.25% in homology, and 57.50% - 67.50% in isolates 9 and all others, and both the patients had histories of large-quantity blood transfusion. CONCLUSION: Blood transfusion was the primary risk factor for HCV infection in HD patients, but iatrogenic transmission of HCV through HD environment could also exist.

Adult↗

PubMed1999

[Effects of environmental lead exposure in kindergartens on children's blood lead level].

OBJECTIVE: To determine if kindergartens' environmental status can influence children's lead exposure. METHODS: Environmental specimens, such as floor dust, peeled-off paint chip, soil and drinking water, as well as children's hand dust and blood samples, were collected and measured for their lead levels in 19 kindergartens, to analyze the relationship between children's blood lead levels and their environmental lead exposure. RESULTS: Geometric means of lead concentrations in indoor floor dust, peeled-off paint chip, dust fallout, outdoor floor dust, soil and drinking water were 86.5 microg/m(2), 235.5 microg/g, 445.9 microg/g, 172.4 microg/m(2), 70.1 microg/g and 12.5 microg/L, respectively. Lead level on children's hands averaged 3.4 microg at both hands. Blood lead levels in children correlated positively with the lead concentrations of outdoor floor dust and their hand dust, with correlation coefficients of 0.5186 and 0.2206, respectively. Multiple regression analysis showed that hand dust lead level in children entered the regression model with a largest standardized partial regression coefficient of 0.3842 and a coefficient of determination of 0.673 for the full equation with F = 6.52 and P < 0.01. CONCLUSION: Status of environmental health in kindergartens plays an important role in children's lead exposure. It is necessary to offer health education for children and make them wash their hands often and overcome unhealthy behavior of sucking their fingers.

Child Day Care Centers↗

PubMed1999

[Effects of lead exposure on their brain-stem auditory evoked potential in children].

OBJECTIVE: To determine if low lead exposure can influence auditory development in children. METHODS: Children were divided into two groups, i.e., low (< 0.483 micromol/L) and high (>or= 0.483 micromol/L) blood lead levels with atomic spectrophotometry (AAS). Latencies and latent intervals between peak waves of their brain-stem auditory evoked potentials (BAEP) in the two groups were measured and compared. RESULTS: There was positive correlation between blood lead levels and BAEP in wave III at right ear, wave V at both right and left ears and latent intervals between peak waves I to V, with correlation coefficients of 0.2991, 0.2748, 0.3248, 0.2064 and 0.2412, respectively. There was significant difference in latencies of wave III at right ear, wave V at both right and left ears and latent intervals between peak waves I to V at both right and left ears and those between waves of III to V at right ear in the low blood lead group. Latencies and latent intervals between peak waves were longer in the high blood level group (with a mean of 0.78 micromol/L and a range of 0.58 to 1.42 micromol/L) than those in the low one (with a mean of 0.30 micromol/L and a range of 0.17 to 0.45 micromol/L). CONCLUSION: Elevated blood lead level could cause prolongation of latencies and latent intervals between peak waves of BAEP and slowdown of the nerve conduction velocity, and so auditory development was influenced.

Child↗

PubMed1999

[RAPD analysis of germplasm in "baizhi"].

OBJECTIVE: To analyse the germplasm in Baizhi. METHOD: Using 12 random primers, over seventeen individuals' RAPD were detected in four populations from wild Baizhi (Angelica dahurica), Qi Baizhi and Hang Baizhi. RESULTS: A total of 40 loci were amplified, 26 of which were polymorphism(65%). The PPS values of Hang Baizhi and Qi Baizhi indicate their low levels of genetic diversity. According to the RAPDinstance analysis, the genetic distance(0.16) between Qi Baizhi and Hang Baizhi is shorter than that of the individuals of the populations of Qi Baizhi and Hang Baizhi, and all of these genetic distances are shorter than those between wild Baizhi and Hang Baizhi(Qi Baizhi). CONCLUSION: Hang Baizhi- and Qi Baizhi belong to the same taxon, which is different from the wild Baizhi.

Angelica↗

PubMed1999

[Effect of 15-methyl PGF2 alpha methyl ester combined with tyrosine hydrazide on early pregnancy in mice].

OBJECTIVE: To observe the effect of 15-methyl PGF2 alpha methyl ester (PG05) in combination with tyrosine hydrazide (TH) on early pregnancy in mice. METHODS: The pregnancy rate of mice treated with PG05 and TH was counted and serum progesterone level was measured by RIA. RESULTS: Administration of TH at 90 mg.kg.day-1 to mice on day 7-9 of gestation enhanced significantly the termination of early pregnancy induced by PG05 at 0.2 mg-1.kg-1 for 2 days. Serum progesterone level of mice treated with PG05 combined with TH was found to be markedly lower than that of animals given PG05 or TH alone. TH at 30 micrograms-1.ml-1 inhibited significantly the activity of 3 beta-HSD of luteal cells in rat. However, PG05 at 10 micrograms-1.ml-1 had no influence upon inhibitory effect of 3 beta-HSD activity induced by TH. TH at 150 mg-1.kg-1 for 3 days did not affect the progesterone receptor level of utering cytoplasma in pseudopregnant rats. CONCLUSIONS: The inhibitory effect of TH on the production of progesterone may be the main mechanism to terminate early pregnancy when used synergically with PG05.

3-Hydroxysteroid Dehydrogenases↗

PubMed1999

[Pathogenesis and clinical classification of the malignant glaucoma].

PURPOSE: To study the pathogenesis of the malignant glaucoma and the basis for the clinical classification of malignant glaucoma. METHODS: Twelve eyes with malignant glaucoma were examed by ultrasound biomicroscopy (UBM), type A and type B ocular ultrasounographer and other clinical ophthalmic tests and diagnostic therapy. The ocular anatomic structures of all 12 eyes were compared with those of the fellow eyes. RESULTS: Ciliary block were confirmed in four of the twelve eyes (33.3%) with malignant glaucoma while the narrow and small anterior segment were found in the fellow eyes by UBM. Iris lens disphragm anterior displacement were found in the other eight of the twelve eyes (76.6%) and their ciliary bodies were deformed passively. The ciliary bodies and anterior segment of the fellow eyes of these eight eyes were anatomically normal. Diagnostic surgery was performed in seven of the twelve eyes and six cases with fluid existing in the vitreous cavity were identified. CONCLUSION: According to our study, we suggest to classify malignant glaucoma into two tyges. One is ciliary block, which caused by ciliary block and concerned with the narrow and small structure of the anterior segment of eye. The other is lens iris block, which caused by iris lens diaphragm anterior displacement. Both types have the same pathophysiologic characteristics, such as, shallow anterior chamber, posterior chamber disappearance and aqueous humor misdirection to the vitreous cavity. But their pathogengesis may not be completely same.

Adult↗

PubMed1999

[Intraobserver reproducibility study of parameters for measurement of position and height of ciliary process by ultrasound biomicroscopy].

OBJECTIVE: To search for suitable measurement parameters for the study of the position and height of cilliary process by ultrasound biomicroscopy (UBM), to test the intraobserver measurement reproducibility of the new parameters we designed as well as the old ones. METHODS: Five parameters: TCPD, A angle, B angle, theta 4 angle and T value, are measured in 21 pieces of UBM image by one observer on five separate occasions. The intraobserver reproducibility is assessed by calculating the coefficient of variation (CV) and the difference among the parameters is tested by grouped T-test. RESULTS: Among 21 images, parameter A angle and T value have no image with CV > 10%, TCPD and B angle have 2 respectively and theta 4 angle has 5. As to average variation level, A angle is lower than TCPD, theta 4 angle is higher than TCPD, both differences of which are significant, and B angle and TCPD are about the same level, the difference between them is not significant. CONCLUSION: Among all the parameters reflecting the position of ciliary process in UBM image, A angle has the best intraobserver reliability, TCPD and B angle are less reliable, theta 4 angle has the worst reliability. The parameter reflecting the height of ciliary process, T value has very good intraobserver reliability.

Adolescent↗

PubMed1999

[Implantation of the molteno tube for refractory glaucoma following penetrating keratoplasty].

PURPOSE: To assess the surgical effectiveness of the molteno tube implantation in glaucoma secondary to penetrating keratoplasty. METHODS: 9 eyes in critical condition with glaucoma secondary to corneal graft surgery, whose intraocular pressures (IOP) have previously failed to respond to glaucoma medication, were undergone Molteno tube implantation. RESULTS: IOPs ranged from 0.8-2.8 kPa (1 kPa = 7.5 mmHg) were obtained in 7 eyes, the success rate accounted for 7/9, 2 eyes still required installation of beta-blocker, the graft rejection occurred in one eye and was remedied with medical treatment, the graft remained half-transparent in one eye. Visual acuity improved in 4 eyes, stayed the same in 4 eyes and was worse in one eye. The best corrected visual acuity over 0.05 was recorded in 4 eyes. CONCLUSION: Moltemo tube implantation is a rational and effective method for preserving a certain level of visual acuity in patients with glaucoma following penetrating keratoplasty.

Adult↗

PubMed1999

[The CT scan of the agger cell and its adjacent structure in endoscopic paranasal sinus surgery].

OBJECTIVE: To promote the development of endoscopic frontal sinus surgery and naso-lacrimal anastomosis surgery by studying the agger cells and their adjacent structures. METHODS: One hundred patients were observed by the continuous coronal CT scan and sagittal CT scan of the paranasal sinuses. Among them, 30 had deviation of nasal septum; 40 had chronic nasosinusitis. There were 80 adult and 20 children. RESULTS: (1) The agger cells existed in 99% of the cases, the development of the agger cells in 9-16 years old children, and adult had no difference; (2) The morphology of agger cells differed widely, but its relationship to the anterior border of the middle nasal concha, bulla ethmoidalis and nasolacrimal canal was quite stable; (3) The upward pneumatization of the agger cells was not related to deviation of nasal septum, but closely related to the development of the frontal sinus; (4) The anterior nasosinusitis often influenced the agger cells and might result in hyperosteogeny. CONCLUSION: The agger cells situated at the pathway of the intranasal frontal sinus during surgery and dacryocystorhinostomy, the nasal CT scan might be beneficial to the prevention of surgical complications.

Adolescent↗

PubMed1998

Poly(vinyl alcohol) nanoparticles prepared by freezing-thawing process for protein/peptide drug delivery.

Poly(vinyl alcohol) (PVA) hydrogel nanoparticles have been prepared by using a water-in-oil emulsion technology plus cyclic freezing-thawing process. The PVA hydrogel nanoparticles prepared by this method are suitable for protein/peptide drug delivery since formation of the hydrogel does not require crosslinking agents or other adjuvants and does not involve any residual monomer. Particularly, there is no emulsifier involved in this new method. Bovine serum albumin (BSA), as a model protein drug, is incorporated into the PVA hydrogel nanoparticles. The PVA hydrogel nanoparticles possess a skewed or log-normal size distribution. The average diameter of the PVA hydrogel nanoparticles is 675.5+/-42.7 nm. Protein drug loading efficiency in the PVA hydrogel nanoparticles is 96.2+/-3.8%. The PVA hydrogel nanoparticles swell in an aqueous solution and the swelling degree increases with the increase of temperature. In vitro release studies show that the BSA release from the nanoparticles can be prolonged to 30 h. The BSA release follows a diffusion-controlled mechanism. The number of freezing-thawing cycle and release temperature both influence BSA release rate considerably. Less freezing-thawing cycle or higher release temperature leads to faster drug release. The BSA is stable during preparation of the PVA hydrogel nanoparticles.

Chemical Phenomena↗

PubMed1998

Liver-specific overexpression of scavenger receptor BI decreases levels of very low density lipoprotein ApoB, low density lipoprotein ApoB, and high density lipoprotein in transgenic mice.

Scavenger receptor BI (SR-BI) is known to mediate the selective uptake of high density lipoprotein (HDL) cholesteryl ester (CE) in liver and steroidogenic tissues. To evaluate the role of SR-BI in plasma lipoprotein metabolism, we have generated transgenic mice with liver-specific overexpression of murine SR-BI. On a chow diet SR-BI transgenic (SR-BI Tg) mice have decreased HDL-CE, apoA-I, and apoA-II levels; plasma triglycerides, low density lipoprotein (LDL) cholesterol, and very low density lipoprotein (VLDL) and LDL apoB were also decreased, compared with control mice. Turnover studies using non-degradable CE and protein labels showed markedly increased total and selective uptake of HDL-CE in the liver and increased HDL protein catabolism in both liver and kidney. To evaluate the changes in apoB further, mice were challenged with high fat, high cholesterol diets. In SR-BI Tg mice plasma apoB levels were only 3-15% of control levels, and the dietary increase in VLDL and LDL apoB was virtually abolished. These studies show that steady state overexpression of hepatic SR-BI reduces HDL levels and increases reverse cholesterol transport. They also indicate that SR-BI can play a role in the metabolism of apoB-containing lipoproteins. The dual effects of increased reverse cholesterol transport and lowering of apoB-containing lipoproteins that result from hepatic SR-BI overexpression could have anti-atherogenic consequences.

Animals↗

PubMed1998

Design and characterization of alpha-melanotropin peptide analogs cyclized through rhenium and technetium metal coordination.

alpha-Melanocyte stimulating hormone (alpha-MSH) analogs, cyclized through site-specific rhenium (Re) and technetium (Tc) metal coordination, were structurally characterized and analyzed for their abilities to bind alpha-MSH receptors present on melanoma cells and in tumor-bearing mice. Results from receptor-binding assays conducted with B16 F1 murine melanoma cells indicated that receptor-binding affinity was reduced to approximately 1% of its original levels after Re incorporation into the cyclic Cys4,10, D-Phe7-alpha-MSH4-13 analog. Structural analysis of the Re-peptide complex showed that the disulfide bond of the original peptide was replaced by thiolate-metal-thiolate cyclization. A comparison of the metal-bound and metal-free structures indicated that metal complexation dramatically altered the structure of the receptor-binding core sequence. Redesign of the metal binding site resulted in a second-generation Re-peptide complex (ReCCMSH) that displayed a receptor-binding affinity of 2.9 nM, 25-fold higher than the initial Re-alpha-MSH analog. Characterization of the second-generation Re-peptide complex indicated that the peptide was still cyclized through Re coordination, but the structure of the receptor-binding sequence was no longer constrained. The corresponding 99mTc- and 188ReCCMSH complexes were synthesized and shown to be stable in phosphate-buffered saline and to challenges from diethylenetriaminepentaacetic acid (DTPA) and free cysteine. In vivo, the 99mTcCCMSH complex exhibited significant tumor uptake and retention and was effective in imaging melanoma in a murine-tumor model system. Cyclization of alpha-MSH analogs via 99mTc and 188Re yields chemically stable and biologically active molecules with potential melanoma-imaging and therapeutic properties.

Amino Acid Sequence↗

PubMed1998

Essential and partially overlapping role of CD3gamma and CD3delta for development of alphabeta and gammadelta T lymphocytes.

CD3gamma and CD3delta are two highly related components of the T cell receptor (TCR)-CD3 complex which is essential for the assembly and signal transduction of the T cell receptor on mature T cells. In gene knockout mice deficient in either CD3delta or CD3gamma, early thymic development mediated by pre-TCR was either undisturbed or severely blocked, respectively, and small numbers of TCR-alphabeta+ T cells were detected in the periphery of both mice. gammadelta T cell development was either normal in CD3delta-/- mice or partially blocked in CD3gamma-/- mice. To examine the collective role of CD3gamma and CD3delta in the assembly and function of pre-TCR and in the development of gammadelta T cells, we generated a mouse strain with a disruption in both CD3gamma and CD3delta genes (CD3gammadelta-/-). In contrast to mice deficient in either CD3gamma or CD3delta chains, early thymic development mediated by pre-TCR is completely blocked, and TCR-alphabeta+ or TCR-gammadelta+ T cells were absent in the CD3gammadelta-/- mice. Taken together, these studies demonstrated that CD3gamma and CD3delta play an essential, yet partially overlapping, role in the development of both alphabeta and gammadelta T cell lineages.

Animals↗

PubMed1998

The X-linked lymphoproliferative-disease gene product SAP regulates signals induced through the co-receptor SLAM.

In addition to triggering the activation of B- or T-cell antigen receptors, the binding of a ligand to its receptor at the cell surface can sometimes determine the physiological outcome of interactions between antigen-presenting cells, T and B lymphocytes. The protein SLAM (also known as CDw150), which is present on the surface of B and T cells, forms such a receptor-ligand pair as it is a self-ligand. We now show that a T-cell-specific, SLAM-associated protein (SAP), which contains an SH2 domain and a short tall, acts as an inhibitor by blocking recruitment of the SH2-domain-containing signal-transduction molecule SHP-2 to a docking site in the SLAM cytoplasmic region. The gene encoding SAP maps to the same area of the X chromosome as the locus for X-linked lymphoproliferative disease (XLP) and we found mutations in the SAP gene in three XLP patients. Absence of the inhibitor SAP in XLP patients affects T/B-cell interactions induced by SLAM, leading to an inability to control B-cell proliferation caused by Epstein-Barr virus infections.

Amino Acid Sequence↗

PubMed1998

Biliary cholesterol excretion: a novel mechanism that regulates dietary cholesterol absorption.

The regulation of dietary cholesterol absorption was examined in C57BL/6 and transgenic mice with liver overexpression of the scavenger receptor BI (SR-BI Tg). In C57BL/6 animals, feeding 0.02 to 1% (wt/wt) dietary cholesterol resulted in a dose-dependent decrease in the percentage of dietary cholesterol absorbed. A plot of total daily mass of dietary cholesterol absorbed versus the percentage by weight of cholesterol in the diet yielded a curve suggesting a saturable process with a Km of 0.4% (wt/wt) and a Vmax of 0.65 mg cholesterol/g body weight per day. Dietary cholesterol suppressed hepatic 3-hydroxy-3-methylglutaryl CoA reductase activity, stimulated cholesterol 7alpha-hydroxylase activity, and enhanced fecal excretion of bile acids, but none of these changes correlated with the percentage of dietary cholesterol absorption. Dietary cholesterol also caused an increase in biliary cholesterol concentration, and in this case the concentration of biliary cholesterol was strongly and inversely correlated with the percentage dietary cholesterol absorption (r = -0.63, P < 0.0001). Biliary cholesterol concentration was also directly correlated with daily cholesterol intake, dietary cholesterol mass absorption, and liver cholesterol ester content. Transgene-induced overexpression of SR-BI resulted in a stimulation of excretion of cholesterol into the bile and suppressed percentage dietary cholesterol absorption. Furthermore, biliary cholesterol levels in SR-BI Tg mice were strongly and inversely correlated with the percentage of dietary cholesterol absorbed (r = -0.99, P < 0.0008). In summary, these results suggest that the excretion of cholesterol into the bile plays an important role in regulating the percentage absorption of dietary cholesterol.

Animals↗

PubMed1998

Induction of apoptosis by Elk-1 and deltaElk-1 proteins.

Elk-1, an ets related gene codes for at least two splice variants Elk-1, which regulates c-fos transcription and deltaElk-1, both of which function as transcriptional activators. To investigate the role of Elk-1 and deltaElk-1 proteins in apoptosis; we have developed rat fibroblast cell lines and human breast cancer cell lines expressing Elk-1 and deltaElk-1. The expression of Elk-1 and deltaElk-1 proteins in the Elk-1/deltaElk-1 transfectants were analysed by immunofluorescence, immunohistochemistry, and Western blot analysis. The Elk-1 unlike deltaElk-1 transfectants showed a shortened and flattened morphology compared to the parental cells. We have found that calcium ionophore treatment of Rat-1 Elk-1, MCF-7 Elk-1, Rat-1 deltaElk-1 and MCF-7 deltaElk-1 transfectants resulted in programmed cell death. These results indicate that constitutive expression of Elk-1 and deltaElk-1 proteins triggers apoptosis in Rat-1 fibroblasts and breast cancer cells when treated with calcium ionophore.

Animals↗

PubMed1998

Chromosome 16q24 deletion and decreased E-cadherin expression: possible association with metastatic potential in prostate cancer.

BACKGROUND: Deletion of chromosome 16q is a frequent aberration in prostatic carcinoma, indicating the existence of candidate tumor suppressor genes involved in the pathogenesis of prostate cancer. METHODS: Chromosome 16 numerical aberration and loss of 16q were studied by fluorescence in situ hybridization in 31 primary and 22 metastatic tumors from 53 patients. The results were compared with E-cadherin expression, tumor grade and stage, and DNA ploidy. RESULTS: Numerical chromosome 16 aberrations, 16q deletion, and loss of E-cadherin expression were found in 29%, 35%, and 29% of the primary tumors, respectively, and in 73%, 73%, and 73% of the metastases, respectively. High tumor grade and DNA aneuploidy were also found to have significant correlation with metastases. CONCLUSIONS: Deletion of chromosome 16q24 and/or loss of the E-cadherin function appears in a high frequency in metastases of prostate cancer. The strong correlations suggest that they may be important risk factors, contributing to the metastatic potential of the tumor.

Adenocarcinoma↗