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Biomedical subjects

N L Wang

Publications and source records attributed to N L Wang.

At least 19 recordsLinked to original sources
PubMed2006

Down-regulation of prostate specific antigen in LNCaP cells by flavonoids from the pollen of Brassica napus L.

The pollen of Brassica napus L. has been used in China to treat benign prostatic hyperplasia (BPH) for over decades. In this study, the pollen of Brassica napus L. was extracted successively with chloroform, ethyl acetate and ethanol. The ethyl acetate extract showed strong activity in decreasing the secretion of prostate specific antigen (PSA) in LNCaP cells as compared to two other extracts, measured by ELISA with finasteride as positive control in the assay. Five flavonoids were subsequently isolated from the active extract using bioassay-guided fractionation. They were Naringenin (1); Luteolin (2); Kaempferol (3); Kaempferol 3-(3-E-p-coumaroyl-alpha-L-rhamnopyranoside) (4); and Kaempferol 3-(2,3-di-E-p-coumaroyl-alpha-L-rhamnopyranoside) (5). All these compounds inhibited PSA secretion significantly, with IC50 values in the range of 5-50 microM. Compounds 2, 4 and 5 showed moderate cytotoxicity to LNCaP cells within the active concentration range, while compounds 1 and 3 showed no cytotoxicity. Further studies on the mechanism action of these compounds were performed by evaluating their activation of estrogen receptor (ER) and antagonistic activities on androgen receptor (AR) in cell-based reporter gene assays. All compounds described here were first isolated from the pollen of Brassica napus L.

Brassica napus↗
PubMed2006

Complete d-band dispersion relation in sodium cobaltates.

We utilize fine-tuned polarization selection coupled with excitation-energy variation of photoelectron signal to image the complete d-band dispersion relation in sodium cobaltates. A hybridization gap anticrossing is observed along the Brillouin zone corner and the full quasiparticle band is found to emerge as a many-body entity lacking a pure orbital polarization. At low dopings, the quasiparticle bandwidth (Fermion scale, many-body E(F) approximately 0.25 eV) is found to be smaller than most known oxide metals. The low-lying density of states is found to be in agreement with bulk-sensitive thermodynamic measurements for nonmagnetic dopings where the 2D Luttinger theorem is also observed to be satisfied.

Journal Article↗
PubMed2006

Low-lying quasiparticle states and hidden collective charge instabilities in parent cobaltate superconductors.

We report a state-of-the-art photoemission (angle-resolved photoemission spectroscopy) study of high quality single crystals of NaxCoO2 the series focusing on the fine details of the low-energy states. The Fermi velocity is found to be small (<0.5 eV A) and only weakly anisotropic over the Fermi surface at all dopings, setting the size of the pair wave function to be on the order of 10-20 nm. In the low-doping regime, the exchange interlayer splitting vanishes and two-dimensional collective instabilities such as 120 degrees -type fluctuations become kinematically allowed. Our results suggest that the unusually small Fermi velocity and the unique symmetry of kinematic instabilities distinguish cobaltates from most other oxide superconductors.

Journal Article↗
PubMed2006

Laser-induced chorioretinal venous anastomosis using combined lasers with different wavelengths.

AIM: To evaluate the effectiveness of combined lasers with different wavelengths in creating chorioretinal venous anastomosis (CRVA) in nonischaemic central retinal vein occlusion (CRVO). METHODS: In this retrospective, noncomparative, consecutive case series, records of all patients with a diagnosis of nonischaemic CRVO who underwent combined laser treatment to induce CRVA and who were followed-up for 6 months or longer were reviewed. RESULTS: Records of 85 patients (85 eyes) were analysed. These patients were divided into two groups. In group 1 (24 cases, 24 eyes), combined lasers with two different wavelengths (argon blue-green laser combined with Nd-YAG laser were used. In group 2 (61 cases, 61 eyes), combined lasers with three different wavelengths (argon blue-green laser combined with krypton red laser and Nd-YAG laser) were used. Functional anastomosis formed in 13 out of 24 eyes (54%) in group 1 and 47 out of 61 eyes (77%) in group 2. In patients with successful anastomosis, visual acuity improved for two or more lines in 49 out of 60 eyes (82%), with the remaining eyes undergoing no change. There were no serious complications. CONCLUSION: The use of three laser wavelengths results in the creation of laser anastomosis and the success rate may be higher than when using two wavelengths alone.

Adolescent↗
PubMed2006

Quasiparticle dynamics in the vicinity of metal-insulator phase transition in NaxCoO2.

Layered cobaltates embody novel realizations of correlated matter on a spin-1/2 triangular lattice. We report a high-resolution systematic photoemission study of the insulating cobaltates. The observation of a single-particle gap opening and band folding provides direct evidence of anisotropic particle-hole instability on the Fermi surface due to its unique topology. Overlap of the measured Fermi surface is observed with the square root 3xsquare root 3 charge-order Brillouin zone near x=1/3 but not at x=1/2 where the insulating transition is actually observed. Unlike conventional density waves, charge stripes, or band insulators, the onset of the gap depends on the quasiparticle's quantum coherence which is found to occur well below the disorder-order symmetry breaking temperature of the crystal (the first known example of its kind).

Journal Article↗
PubMed2004

Infrared probe of the electronic structure and charge dynamics of Na0.7CoO2.

We present measurements of the optical spectra on Na(0.7)CoO(2) single crystals. The optical conductivity shows two broad interband transition peaks at 1.6 eV and 3.1 eV, and a weak midinfrared peak at 0.4 eV. The intraband response of conducting carriers is different from that of a simple Drude metal. A peak at low but finite frequency is observed, which shifts to higher frequencies with increasing temperature, even though the dc resistivity is metallic. The origin of the interband transitions and the low-frequency charge dynamics have been discussed and compared with other experiments.

Journal Article↗
PubMed2004

Metamagnetic transition in Na 0.85 CoO2 single crystals.

We report the magnetization, specific heat, and transport measurements of a high quality Na(0.85)CoO2 single crystal in applied magnetic fields up to 14 T. At high temperatures, the system is in a paramagnetic phase. It undergoes a magnetic phase transition below approximately 20 K. For the field H||c, the measurement data of magnetization, specific heat, and magnetoresistance reveal a metamagnetic transition from an antiferromagnetic state to a quasiferromagnetic state at about 8 T at low temperatures. However, no transition is observed in the magnetization measurements up to 14 T for H perpendicular c. The low temperature magnetic phase diagram of Na(0.85)CoO2 is determined.

Journal Article↗
PubMed2004

Infrared spectroscopy of the charge ordering transition of Na0.5CoO2.

We report infrared reflectivity study of charge ordering in a Na0.5CoO2 single crystal. In comparison with x=0.7 and 0.85 compounds, we found that the effective carrier density increases systematically with decreasing Na contents. The charge ordering transition only affects the optical spectra below 1000 cm(-1). A hump near 800 cm(-1) develops below 100 K, which is accompanied by the appearance of new lattice modes as well as the strong antiresonance feature of phonon spectra. These observations signify a polaronic characteristic of charge carriers. Below T(co), an optical gap develops at the magnitude of 2Delta approximately 3.5k(B)T(co) (T<<T(co)), evidencing an insulating charge density wave ground state.

Journal Article↗
PubMed2002

Oxygen isotope effect in the ab-plane reflectance of underdoped YBa(2)Cu(3)O(7-delta).

We have measured the effect of oxygen isotope substitution on the ab-plane reflectance of underdoped YBa(2)Cu(3)O(7-delta). The frequency shift of the transverse optic phonons due to the substitution of 16O by 18O yields an isotope effect of the expected magnitude for copper-oxygen stretching modes with alpha=0.5+/-0.1. The reflectance shoulder at 400-500 cm(-1) shows a much smaller exponent of alpha=0.1+/-0.1 in the normal state and alpha=0.23+/-0.1 in the superconducting state. These observations suggest that the shoulder is of electronic origin and not due to a phonon mode as has been suggested recently.

Journal Article↗
PubMed2002

Microorganisms in a high altitude glacier ice in Tibet.

Eighty-one strains of viable microorganisms were recovered from 23 samples collected from Ice Core 3 of Malan Glacier (China, 91 degrees 45.3' E, 35 degrees 48.4' N) drilled at high altitude (5620 m). All the strains were prokaryotes--75 of bacteria (including spore-forming ones) and 6 of actinomycetes. The characteristic genera differ from those of Arctic and Antarctic ice, in which many fungi and algae are widely distributed; this shows an difference of environmental conditions between Tibet and polar regions. The variation in number and species of Bacillus in different ice core layers implied changes of environmental conditions in the past.

Bacteria↗
PubMed2001

[Studies on the active polysaccharides from Lycium barbarum L].

AIM: To investigate the structures and immunomodulation activity of four homogeneous polysaccharides: LBP 1a-1, LBP 1a-2, LBP 3a-1 and LBP 3a-2 isolated from Lycium barbarum L. brought from Zhongning County, Ningxia Province. METHODS: Their molecular weights, sugar component (constituents) and their linkages were determined by gel permeation chromatography, acid hydrolysis, periodate oxidation and NMR spectrum. The activity of immunomodulation was evaluated with splenocyte proliferation by [3H]-TDR incorperation, in vitro. RESULTS: Four polysaccharides with molecular weights 11.5 x 10(4), 9.4 x 10(4), 10.3 x 10(4) and 8.2 x 10(4), were shown to enhance splenocyte proliferation induced by ConA. LBP 1a-1 and LBP 1a-2 were alpha-(1-->6)-D-glucans. LBP 3a-1 and LBP 3a-2 were found to be a-(1-->4)-D-polygalacturonans. CONCLUSION: The four polysaccharides were first isolated from this plant. Polysaccharides with main chain of alpha-(1-->4)-D-polygalacturonans showed stronger immunomodulation activity.

Adjuvants, Immunologic↗
PubMed2000

Dilatation of the biliary tree in children: sonographic diagnosis and its clinical significance.

We evaluated sonographically 162 children who met the criteria for biliary tract dilatation in the past 18 years. Of these, 131 patients were diagnosed as having anomalous dilatations of the biliary tree (including 112 with choledochal cysts and 19 with biliary duct dilatation and biliary atresia). Biliary tract dilatations in the other 31 patients were due to secondary causes or normal variants. All cases of intrahepatic biliary tree dilatation and those with both intra- and extrabiliary duct dilatations were anomalous. In 117 cases of extrahepatic biliary tract dilatation only, the mean diameter was widest in cases of choledochal cyst (21.4 +/- 12.1 mm, compared with cases of biliary tract dilatation with biliary atresia (10 +/- 2.4 mm), secondary biliary duct dilatation (8.5 +/- 1.5 mm), and normal variants (4.4 +/- 1.2 mm) (P < 0.001). Of the 43 infants with biliary tree dilatation, 24 (56%) had choledochal cysts and 19 (44%) had biliary tract dilatation associated with biliary atresia. Excluding cases associated with biliary atresia, the accuracy of diagnosing choledochal cysts in extrahepatic biliary tract dilatation was 71% and 97% using cutoffs of 7 mm and 10 mm as the minimum diameter, respectively.

Bile Ducts↗
PubMed2000

[Determination of furostanol saponins in Bulbus Allii Macroste].

OBJECTIVE: To establish an Ehrlich reaction-colorimetry method for determining furostanol saponins in Bulbus Allii Macroste. METHOD: Based on the coloration reaction between furostanol saponins and p-dimethylaminobenzaldehyde, the UV detection wavelength used was 515 nm, and the optimum conditions were selected on homogeneous design principle. RESULT: The standard curve of macrostemonoside G was linear in the concentration range of 0.1975-0.9880 mg.ml-1. The average recovery was 97.7% (RSD = 3.65%). CONCLUSION: The method is rapid, accurate and easy to operate.

Allium↗
PubMed1999

Gastro-intestinal bleeding caused by leiomyoma of the small intestine in a child with neurofibromatosis.

UNLABELLED: Gastro-intestinal bleeding is an uncommon presentation in children with neurofibromatosis. Gastro-intestinal involvement caused by jejunal leiomyoma has only been described in adults. To the best of our knowledge, this is the first paediatric case of jejunal leiomyoma associated with neurofibromatosis. We present a 10-year-old girl with a 9-month history of anaemia and low gastro-intestinal bleeding. Abdominal sonography and small bowel series showed a submucosal mass in the proximal jejunum. On surgery, a submucosal tumour was excised and histological examination suggested a diagnosis of "smooth muscle tumour of undetermined malignant potential". There were no recurrence of symptoms for 4 years after the operation. CONCLUSION: Jejunal leiomyoma should be considered in a child with neurofibromatosis presenting with gastro-intestinal bleeding.

Child↗
PubMed1999

Sigmoid adhesion caused by a congenital mesocolic band.

Congenital mesocolic band is an uncommon aberration in the development of the mesentery. Large-bowel obstruction secondary to adhesion and/or congenital band is very rare in children. A 6-month-old male infant who had no history of previous surgery was admitted with unremitting crying. A barium enema showed extraintestinal compression of the sigmoid colon. Laparotomy revealed an adhesive mesocolic band compressing the proximal part of the sigmoid colon. The band was lysed. The patient has remained asymptomatic since the procedure.

Diagnosis, Differential↗
PubMed1998

Results of surgery for vesicoureteral reflux in children: 6 years' experience in an Asian country.

From January 1990 to December 1995, a total of 181 patients underwent reimplantation of 318 ureters for primary vesicoureteral reflux (VUR); 87.8% received bilateral reimplantation. Surgical indications included breakthrough infection (35%), high-grade (> or = IV) reflux (33%), or both (29%). The operative success rate was 99.4% at 3 months postoperatively and 100% ultimately. The complications included: contralateral sequential reflux in 3.9%, postoperative bladder diverticula in 1.1%, postoperative urinary infection in 1.1%, residual reflux in 0.3%, postoperative vesicoureteral stenosis in 0.3%, and slippage of the drainage tube in 0.3% of cases. Two patients had renal failure due to VUR that was proven by renal biopsy (one 4-year-old and one 8-year-old). The incidence of associated anomalies was higher than in the normal population. The average number of hospital admission days was 7.9 (3-63). After 1992, no ureteral stent was left in postoperatively. All patients received prophylactic antibiotics for 3 months postoperatively until the VUR disappeared. The surgical results were satisfactory in this series.

Adolescent↗