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Jianhua Wu

Publications and source records attributed to Jianhua Wu.

13 recordsLinked to original sources
PubMed2006

Detecting correlation changes in electrophysiological data.

A correlation multi-variate analysis of variance (MANOVA) test to statistically analyze changing patterns of multi-electrode array (MEA) electrophysiology data is developed. The approach enables us not only to detect significant mean changes, but also significant correlation changes in response to external stimuli. Furthermore, a method to single out hot-spot variables in the MEA data both for the mean and correlation is provided. Our methods have been validated using both simulated spike data and recordings from sheep inferotemporal cortex.

Action Potentials↗
PubMed2006

Equilibrium geometries and associated energetic properties of mixed metal-silicon clusters from global optimization.

The structural properties of the cluster series Me(m)Si(7-m) (Me = Cu and Li, m < or = 6) are studied by density functional theory (DFT) employing a plane wave basis. The equilibrium geometries and energetic properties of these clusters are obtained by use of the simulated annealing procedure in conjunction with the Nosé thermostat algorithm. The lowest energy isomer thus obtained is analyzed by density functional theory at the B3LYP/6-311+G(d,p) level including all electrons. Pentagonal ground state structures derived from the D(5)(h) equilibrium geometries of both Si(7) and Cu(7) are obtained for Cu(m)Si(7-m) with m < 6. The Li(m)Si(7-m) clusters, in contrast, tend toward adsorption geometries where m Li atoms are attached to a Si(7-m)framework with pronounced negative charge. For both Li(m)Si(7-m) and Cu(m)Si(7-m), a marked decrease of the energy gap is found as the number of metal atom constituents increases.

Algorithms↗
PubMed2006

The sclerosing variant of adenoid cystic carcinoma: a previously unrecognized neoplasm of major salivary glands.

We report 2 cases of a previously unrecognized sclerosing variant of adenoid cystic carcinoma (ACC) of major salivary glands. One of the tumors arose in the parotid and the other in the submaxillary gland of young adult patients. The tumors were composed predominantly of varying-sized large sclerotic and hypocellular nodules containing myoepithelial cells and pseudovascular spaces, most likely the result of artifactual retraction. In moderately cellular nodules, there were numerous small globules or spherules surrounded by myoepithelial cells similar to those of collagenous or mucinous spherulosis. Focal cribriform areas and ductal structures lined by epithelial cells were also identified. Both tumors showed perineural invasion. Electron microscopy revealed that both large nodules and small globules or spherules were composed of excessive amounts of basement membrane and thick-banded collagen fibers. The myoepithelial cells showed immunoreactivity for smooth muscle actin (SMA), S100 protein, and vimentin. Collagen IV showed variable reactivity in both the large nodules and small spherules. More cases of the sclerosing variant of ACC and long-term follow-up of the patients are needed to determine the biologic behavior of this unusual but distinctive variant of ACC.

Adult↗
PubMed2006

Giant cell tumor of the extrahepatic biliary tree: a clinicopathologic study of 4 cases and comparison with anaplastic spindle and giant cell carcinoma with osteoclast-like giant cells.

We report four previously undescribed primary giant cell tumors of the extrahepatic biliary tree and morphologically compare them with 10 anaplastic spindle and giant cell carcinomas with osteoclast-like giant cells of the gallbladder. Two giant cell tumors were located in the distal common bile duct; one in the cystic duct and one in the gallbladder. The 3 patients with bile duct tumors were male, and the only patient with a gallbladder tumor was a female. The age of the patients ranged from 45 to 60 years with an average of 55 years. The patients with bile duct tumors presented with biliary obstruction, and the patient with a gallbladder tumor presented with symptoms of cholelithiasis and a gallbladder mass. Histologically, the tumors were similar to giant cell tumors of bone. They consisted of a mixture of mononuclear and multinucleated osteoclast-like giant cells. The mononuclear cells showed no atypical features, and their nuclei were similar to those of the multinucleated giant cells. CD163 immunoreactivity was restricted to the mononuclear cells, whereas CD68 and HAM 56 labeled only the multinucleated osteoclast-like giant cells. The mononuclear cells were EMA-positive but did not express cytokeratins. Follow-up showed that 3 patients were alive and disease-free 3.7 to 7 years after surgery. The anaplastic spindle and giant cell carcinomas contained a fewer number of osteoclast-like giant cells, and their mononuclear cells showed considerable variation in size and shape, marked cytologic atypia, and numerous mitotic figures. They were focally cytokeratin positive (AE1/AE3; CAM 5.2) and did not label with CD163, CD68, and HAM 56. The benign osteoclast-like giant cells showed immunoreactivity for CD68 and HAM 56 but were negative for CD163 and cytokeratins. Giant cell tumors of the extrahepatic biliary tree are benign true histiocytic neoplasms that should be distinguished from the highly lethal anaplastic spindle and giant cell carcinomas with osteoclast-like giant cells by detailed cytologic analysis and immunohistochemical stains for CD163, CD68, HAM 56, and cytokeratins.

Adenocarcinoma↗
PubMed2006

The many faces and mimics of papillary thyroid carcinoma.

This article provides an overview of the 15 histologic variants of papillary thyroid carcinoma listed by the 2004 World Health Organization (WHO) monograph on endocrine tumors. The histologic features, differential diagnosis, and clinical course of each variant are discussed in some detail. The follicular variants (conventional and macrofollicular) constitute a morphologic challenge because the majority of these tumors are encapsulated and, also, because, in many tumors, not all neoplastic cells show the nuclear features considered to be diagnostic of papillary carcinoma. As a result, most of these tumors are missed even by experienced pathologists. Moreover, hyperplastic thyroid lesions, follicular adenomas, and Hashimoto's thyroiditis may contain cells with clear nuclei resembling those of papillary carcinoma. Papillary carcinomas composed entirely of hyperchromatic cells have been overlooked. The WHO monograph defines papillary carcinoma with focal spindle and giant cell carcinoma components but its clinical behavior is unknown. Papillary carcinoma with an insular pattern that does not show the artifactual separation of the cell nests has been misinterpreted as the solid variant of papillary carcinoma. Papillary microcarcinomas include not only the conventional type and the follicular variants but also the tall cell and columnar cell variants.

Adenocarcinoma, Papillary↗
PubMed2006

Changes in step variability of new walkers with typical development and with Down syndrome.

Models of human gait are based on adult locomotion. C. E. Bauby and A. D. Kuo (2000) proposed that adults rely on passive mechanisms at the spinal level to control motion in the anteroposterior direction and rely on direct monitoring of postural control in the lateral direction. The authors' purpose in this study was to determine if that model applies to control at the onset of walking in typically developing toddlers (n = 9) and in toddlers with Down syndrome (n = 6). Their longitudinal data suggested that toddlers control gait in a distinctly different manner than adults do. An adult pattern of control emerges with experience. In addition, the effect of experience on the emergence of that pattern is magnified by task-specific early intervention. The present data support the emergence and discovery of efficient patterns of control in this fundamental human behavior.

Down Syndrome↗
PubMed2005

Measuring molecular elasticity by atomic force microscope cantilever fluctuations.

In single-molecule mechanics experiments the molecular elasticity is usually measured from the deformation in response to a controlled applied force, e.g., via an atomic force microscope cantilever. We have tested the validity of an alternative method based on a recently developed theory. The concept is to measure the change in thermal fluctuations of the cantilever tip with and without its coupling to a rigid surface via the molecule. The new method was demonstrated by its application to the elasticity measurements of L- and P-selectin complexed with P-selectin glycoprotein ligand-1 or their respective antibodies, which showed values comparable to those measured from the slope of the force-extension curve. L- and P-selectin were found to behave as nearly linear springs capable of sustaining large forces and strains without sudden unfolding. The measured spring constants of approximately 4 and approximately 1 pN/nm for L- and P-selectin, respectively, suggest that a physiological force of approximately 100 pN would result in an approximately 200% strain for the respective selectins.

Calibration↗
PubMed2005

Intestinal and oncocytic variants of pancreatic intraepithelial neoplasia. A morphological and immunohistochemical study.

We report 2 previously undescribed morphological variants of pancreatic intraepithelial neoplasia (PanIN). The first variant with an intestinal phenotype was associated with mucinous carcinomas that occurred in the tail of the pancreas of 2 men (60 and 65 years old). The carcinomas lacked the characteristic ovarian-like stroma of mucinous cystic neoplasms observed in female patients and did not show a papillary architecture. Whether they represent mucinous cystadenocarcinomas or mucinous carcinomas that arose from the flat variant of intraductal papillary mucinous neoplasms could not be determined with certainty. Microscopically, the intestinal type of PanIN was composed of pseudostratified columnar cells similar to those of colonic adenomas and showing variable degrees of dysplasia. A significant increase in the MIB-1 labeling index correlated with the severity of dysplasia. In contrast to conventional PanIN, the intestinal variant expressed MUC-2 and was MUC-1 negative. The second type of PanIN had an oncocytic phenotype, coexpressed MUC-2 and MUC-1 mucins, and was associated with intraductal oncocytic papillary carcinomas that showed a similar immunohistochemical mucin profile. Both intestinal and oncocytic types of PanIN expressed DPC4 and lacked p53 reactivity. The anatomical separation of the PanINs from the carcinomas and the gradual progression of cytological and architectural abnormalities in both variants of PanIN argue against ductal spread (cancerization of the ducts). The intestinal and oncocytic variants of PanIN broaden the morphological spectrum of this intraductal lesion. Although their significance is unknown, the possibility that these PanIN variants represent cancer precursors should be considered.

Adenocarcinoma, Mucinous↗
PubMed2005

Thermo-mechanical responses of a surface-coupled AFM cantilever.

Atomic force microscopy (AFM) has been widely used for measuring mechanical properties of biological specimens such as cells, DNA, and proteins. This is usually done by monitoring deformations in response to controlled applied forces, which have to be at ultralow levels due to the extreme softness of the specimens. Consequently, such experiments may be susceptible to thermal excitations, manifested as force and displacement fluctuations that could reduce the measurement accuracy. To take advantage of, rather than to be limited by, such fluctuations, we have characterized the thermomechanical responses of an arbitrarily shaped AFM cantilever with the tip coupled to an elastic spring. Our analysis shows that the cantilever and the specimen behave as springs in parallel. This provides a method for determining the elasticity of the specimen by measuring the change in the tip fluctuations in the presence and absence of coupling. For rectangular and V-shaped cantilevers, we have derived a relationship between the mean-square deflection and the mean-square inclination and an approximate expression for the specimen spring constant in terms of contributions to the mean-square inclination from the first few vibration modes.

Computer Simulation↗
PubMed2004

Catch bonds govern adhesion through L-selectin at threshold shear.

Flow-enhanced cell adhesion is an unexplained phenomenon that might result from a transport-dependent increase in on-rates or a force-dependent decrease in off-rates of adhesive bonds. L-selectin requires a threshold shear to support leukocyte rolling on P-selectin glycoprotein ligand-1 (PSGL-1) and other vascular ligands. Low forces decrease L-selectin-PSGL-1 off-rates (catch bonds), whereas higher forces increase off-rates (slip bonds). We determined that a force-dependent decrease in off-rates dictated flow-enhanced rolling of L-selectin-bearing microspheres or neutrophils on PSGL-1. Catch bonds enabled increasing force to convert short-lived tethers into longer-lived tethers, which decreased rolling velocities and increased the regularity of rolling steps as shear rose from the threshold to an optimal value. As shear increased above the optimum, transitions to slip bonds shortened tether lifetimes, which increased rolling velocities and decreased rolling regularity. Thus, force-dependent alterations of bond lifetimes govern L-selectin-dependent cell adhesion below and above the shear optimum. These findings establish the first biological function for catch bonds as a mechanism for flow-enhanced cell adhesion.

Antibodies, Monoclonal↗
PubMed2004

[Characterization and quantitative determination of diesel fractions by comprehensive two-dimensional gas chromatography/time of flight mass spectrometry].

Comprehensive two-dimensional gas chromatography/time of flight mass spectrometry (GC x GC/TOFMS) has been applied for the analysis of diesel fractions. Two GC x GC methods are suggested. One is applied for exhaustive characterization and the other is used for the fast separation and quantitation of groups. No sample cleaning-up was required for both methods. Besides hydrocarbon compounds, the distributions of sulfur compounds and nitrogen compounds in a catalytic cracked diesel oil were investigated using the developed method. A total of 27 nitrogen compounds (including indole, alkyl indoles, carbazole and alkyl carbazoles) and 42 sulfur compounds (including benzothiophene, alkyl benzothiophenes, dibenzothiophene and alkyl dibenzothiophenes) were identified based on TOFMS and retention index. Quantitative determination of non-aromatics, mono-, di- and tri-aromatics of four diesel oils has been performed. The results are in good agreement with those from ASTM D2425 method.

Chromatography, Gas↗
PubMed1995

Topological analysis of the lysine-specific permease of Escherichia coli.

Escherichia coli accumulates lysine via two systems, one specific for lysine (LysP) and a second inhibited by arginine or ornithine (LAO). The lysP gene encodes a polypeptide of 489 residues. A topological analysis of the LysP protein was performed using gene fusions. Random in-frame fusions of the lysP gene with the lacZ or blaM genes were generated. Site-directed mutagenesis was also used to generate additional blaM fusions at specific locations in the lysP gene. Two methods were used to alleviate the problem of lethal expression of some lysP::blaM fusions. First, ternary fusions were constructed in which the arsD gene was fused at the 5' end of the lysP gene and the blaM gene fused at specific sites within the lysP gene. In these plasmids lysP expression was controlled by the ars promoter. Secondly, an E. coli strain with a pcnB mutation was used with some fusions to maintain the plasmids at a reduced copy number. From analysis of 30 gene fusions, a topological model of the LysP protein is proposed in which the protein has 12 membrane-spanning regions, with the N- and C-terminal in the cytosol.

Amino Acid Transport Systems, Basic↗