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Biomedical subjects

N C Wu

Publications and source records attributed to N C Wu.

At least 19 recordsLinked to original sources
PubMed1999

Fine needle aspiration (FNA) biopsy of palpable breast masses: comparison of conventional smears with the Cyto-Tek MonoPrep system.

BACKGROUND: One of the limitations preventing the widespread use of fine-needle aspiration (FNA) is that it requires skill to obtain an adequate sample and well prepared smears. In this study, a new monolayer technique, the Cyto-Tek MonoPrep (MP) system, which obviates the need for smear preparation, was evaluated against conventional smear (CS) preparation for palpable breast lesions. METHODS: A total of 44 paired CS/MP breast FNA specimens were studied. The authors blindly analyzed the CS and the MP slides separately, then by a side-by-side evaluation. The two methods were compared with respect to diagnostic concordance, cellularity, cell preservation, background debris, and time needed to prepare and diagnose each case. RESULTS: An exact diagnostic correlation was present in 34 of 44 (77%) cases. The 10 noncorrelating cases were caused by decreased cellularity in the MP cases; nonetheless, 7 of these were correctly assigned to the right general diagnostic category, whereas the remaining 3 cases had insufficient cells. In addition to overall lesser cellularity on MP, fibroadenoma cases had smaller epithelial sheets and absence of stroma compared with CS. Both methods had comparable cellular preservation and diagnostic evaluation time, but background debris and preparation time were greater for MP. CONCLUSION: CS are favored over MP for the preparation of breast FNA specimens in centers with specialized FNA services because of their higher diagnostic yield, ease of preparation, and availability for immediate cytologic evaluation. However, in settings where specimens are collected sporadically by unskilled clinicians, the MP system may prove to be useful as an alternative or an adjunct to CS. Cancer (Cancer Cytopathol)

Biopsy, Needle↗
PubMed1994

Neuroblastoma cell-mediated leukocyte chemotaxis: lineage-specific differentiation of interleukin-8 expression.

To determine whether neural crest-derived neuroblastoma cells may release cytokines which regulate the function of leukocytes, we found that neuroblastoma (HTB-11) cells did not constitutionally express IL-1 beta, TNF alpha, or IL-8 mRNA. However, TNF alpha, which induced HTB-11 cells to differentiate to perineurium-like cells, induced expression of IL-8 mRNA in a dose- and time-dependent fashion. In contrast, pentoxifylline (1 mM), which promoted HTB-11 cells to differentiate to polygonal neuron-like cells, did not induce IL-8 mRNA expression. As determined by enzyme-linked immunoassay, high levels of IL-8 were detectable in the culture supernatants from TNF alpha-treated neuroblastoma cells, but not pentoxifylline-treated neuroblastoma cells (19.60 +/- 2.34 vs 0.10 +/- 0.06 ng/ml). Culture supernatants obtained from TNF alpha-treated neuroblastoma cells induced chemotaxis of neutrophils and lymphocytes that was significantly blocked by anti-IL-8 neutralizing antibodies. Detection of a leukocyte chemotactic factor was not observed in the culture supernatants from pentoxifylline-treated cells. These results suggest that neural crest-derived perineurium-like cells, but not neuron-like cells, may release a leukocyte chemotactic factor or factors such as IL-8 which could be involved in leukocyte recruitment seen in inflammatory diseases affecting peripheral nerves.

Cell Communication↗
PubMed1993

Studies of carbonic anhydrase inhibitors: physicochemical properties and bioactivities of new thiadiazole derivatives.

A series of thiadiazole derivatives of carbonic anhydrase inhibitors were prepared and their physicochemical properties and pharmacological activities such as corneal permeabilities, inhibition of carbonic anhydrase activities were evaluated. The solubilities and pKa values were determined in varied pH of phosphate buffers at 35 degrees C after equilibrium. Intrinsic solubility and pKa value were calculated from the plot of solubility versus the reciprocal of hydrogen ion concentration. The distribution coefficient was determined in the system of octanol/pH 7.65 phosphate buffer. As a result, the sigma (Hammett constant) and pi (hydrophobic substituent constant) values of substituents were found to be correlated to the logarithm of Ka and partition coefficient. Corneal permeabilities of the analogue were determined in a specially designed diffusion cell using excised rabbit cornea, which ranged from 1.32 x 10(-5) (compound II) to 3.48 x 10(-7) cm/sec (compound VI). Compound with high permeability might be expected to be absorbed well after topical administration into the eye. The methodology of pH-stat was used to determine the inhibition of the carbonic anhydrase activity of the analogue. The IC50 values of the analogue around 10(-8) M as determined were less than that of acetazolamide. The results suggest that the analogue had good pharmacological activity. Finally, an equation for quantitative structure-activity relationship was established for the analogue, which is as follows: [formula: see text]

Absorption↗
PubMed1993

m-Hydroxybenzoylecgonine: an important contributor to the immunoreactivity in assays for benzoylecgonine in meconium.

Meconium has been reported to be a more suitable specimen than maternal or neonatal urine for detecting fetal exposure to cocaine. In a study comparing various immunoassays with gas chromatography/mass spectrometry (GC/MS), several unexplained discrepancies among the assays were noted. Using methanol extracts of meconium samples, an immunoreactive spot that was more polar than benzoylecgonine was detected by thin-layer chromatography (TLC). An extract of this spot analyzed by GC/MS yielded a fragmentation pattern indicative of an aryl hydroxylated benzoylecgonine. Standards of m-hydroxybenzoylecgonine, o-hydroxybenzoylecgonine, and p-hydroxybenzoylecgonine were synthesized; it was determined that m-hydroxybenzoylecgonine had the same retention time and ion ratios as the TLC immunoreactive spot. Furthermore, m-hydroxybenzoylecgonine proved to be immunoreactive. Ten meconium samples immunoreactive for benzoylecgonine were analyzed by GC/MS. Results before and after hydrolysis with beta-glucuronidase (type IX) showed free m-hydroxybenzoylecgonine comprising 59 to 94% of the total m-hydroxybenzoylecgonine and showed total m-hydroxybenzoylecgonine values ranging from 0.2 to 6.3 times as high as benzoylecgonine. Therefore, m-hydroxybenzoylecgonine appears to be a quantitatively important cocaine metabolite in meconium, which is responsible for a significant portion of the discrepancy between benzoylecgonine concentrations in meconium extracts as measured by immunoassay and GC/MS.

Artifacts↗
PubMed1993

Induction of interleukin-8 expression in neuroblastoma cells by retinoic acid: implication of leukocyte chemotaxis and activation.

Neuroblastoma cells in response to retinoic acid (RA) exhibit differentiation. RA, which can promote tumor cell differentiation, has also been shown to regulate tumor-infiltrating leukocytes. In an attempt to explore the relationship between RA-induced neuroblastoma cell differentiation and leukocyte chemotaxis, we investigated expression of IL-1 beta, IL-8, granulocyte-macrophage colony stimulating factor, and tumor necrosis factor-alpha in the undifferentiated and RA-induced differentiated neuroblastoma cells. Using SK-N-SH neuroblastoma cells, we found that RA induced differentiation of SK-N-SH cells as demonstrated by down-regulation of N-myc gene expression, cell-cycle arrest in G1 phase, and phenotypic change. Neither RA-treated nor untreated neuroblastoma cells expressed IL-1 beta, granulocyte-macrophage colony stimulating factor, or tumor necrosis factor-alpha mRNA. RA-treated but not untreated SK-N-SH cells expressed IL-8 mRNA in a time- and dose-dependent fashion. As determined by ELISA, IL-8 levels were detectable in the culture supernatants from RA-treated, but not untreated, neuroblastoma cells (2.65 +/- 0.43 versus 0.05 +/- 0.04 ng/mL). Using neutrophil and lymphocyte chemotactic assays, we found that RA-treated but not untreated culture supernatants of neuroblastoma cells promoted neutrophil and lymphocyte chemotaxis. The RA enhancement of neuroblastoma cell-mediated leukocyte chemotaxis was significantly blocked by anti-IL-8 neutralizing antibodies. These results suggest that RA-induced neuroblastoma cell differentiation is associated with production of functional IL-8, which may be involved in the leukocyte infiltration and activation resulting in tumor regression.

Cell Differentiation↗
PubMed1991

[Calcium and phosphorus levels in serum and urine of patients with chronic cor pulmonale complicated with respiratory insufficiency].

The levels of Ca and P in serum and urine, and the renal functions: Ccr. TRCa and TRP were determined in 43 patients with chronic Cor Pulmonale complicated with respiratory insufficiency. The results showed that the level of SCa decreased in 72.1% (31/43) and after correction by serum protein 58.1% (25/43). The SP was normal in 60.5%, (26/43). UCa and UP reduced in 62.8% (27/43) and 88.4% (38/43) respectively.

Adult↗
PubMed1984

Calcium- and cyclic AMP-regulated protein kinases of bovine central-nervous-system myelin.

Bovine central-nervous-system myelin was found to contain both Ca2+-activated and cyclic AMP-dependent protein kinases. Each enzyme possesses unique solubility and substrate-specificity characteristics. The Ca2+-activated enzyme, like its substrate (basic protein), is probably deeply embedded in the neural membrane, whereas the cyclic AMP-dependent kinase appears to be much less tightly associated with myelin. Treatment of insoluble myelin fraction housing the Ca2+-activated kinase with phospholipase A2 and phospholipases A2 + C causes a decrease in its ability to become activated by Ca2+. This can be countered by phosphatidylserine and phosphatidylethanolamine. Whereas the activity of the Ca2+-activated membrane-associated kinase is inhibited by chlorpromazine, dibucaine, melittin and Triton X-100, it is activated by certain phorbol diesters (4 beta-phorbol 12-myristate 13-acetate, 4 beta-phorbol 12,13-didecanoate, 4 beta-phorbol 12,13-dibenzoate and 4 beta-phorbol 12,13-diacetate), which appear to exert this effect by lowering the concentration of Ca2+ normally required for the activation of this enzyme. Together these results suggest that the activation of the membrane-associated kinase by Ca2+ most probably requires certain lipids, perhaps those already present in the membrane.

Animals↗
PubMed1983

Partial characterization of the phosphotransferase system of human central-nervous-system myelin.

The phosphotransferase system of human central-nervous-system myelin was investigated. Evidence obtained indicated the presence of at least two different phosphotransferase systems (cyclic nucleotide-dependent and -independent) in myelin, which were found to be firmly associated with the membrane. The cyclic AMP-dependent kinase of myelin and white-matter cytosol preferentially phosphorylated certain histone fractions and displayed only modest activity with basic protein as substrate. On the other hand, the cyclic nucleotide-independent system showed specificity toward basic protein. Its activity was not only dependent on Mg2+ but it was greatly enhanced by this bivalent cation. Whereas the cyclic nucleotide-dependent kinase could be extracted with buffers containing Triton X-100, the bivalent cation-regulated kinase resisted solubilization from myelin under these conditions.

Brain↗
PubMed1979

Cell volume decrease during Friend leukemia cell differentiation.

Friend leukemia cells (GM86, clone 745) were induced to differentiate with dimethyl sulfoxide or butyric acid. The kinetics of induction were measured by cell growth, cell volume distributions, and [3H]thymidine incorporation. From the volume distributions, it was found that the rate of induction was both agent sensitive and concentration dependent. The changes in volume distributions occurred approximately 4 hr earlier with dimethyl sulfoxide induction relative to butyric acid induction. However, the changes with the butyric acid induction were more dependent on concentration. A decrease in labeling indices during the 12- to 20-hr time period was correlated to a decrease in mean cell volume and an increase in the proportion of G1 cells. After the 20-hr time period of induction, an increase in labeling indices and in the percentage of large cells was observed. The data suggest that a transient block of cells in G1 occurred between 12 to 20 hr, and that the early differentiation involved a volume decrease which was related to a redistribution of cell cycle stages. The study was also shown that the changes of cell volume are a rapid monitor to determine the early events of the differentiation process.

Animals↗
PubMed1978

Mouse fetal hemoglobin.

Using isoelectric focusing, a fetal hemoglobin was found in the peripheral blood of C57BL/6 fetal mouse during the 14 to 20 days gestational period. In acid-urea polyacrylamide gel the pattern of this fetal hemoglobin was different from that of the adult hemoglobin. The mouse fetal hemoglobin was differentiated from the mouse adult hemoglobin by immunodiffusion reaction. It suggests that there is a transient fetal hemoglobin in the C57BL/6 mouse during gestational age.

Animals↗
PubMed1977

Isolation and characterization of multiple hamster hemoglobins.

Multiple hemoglobins were found in the peripheral blood of hamsters when separated by analytical isoelectric focusing in polyacrylamide gel between pH 6.0 and pH 8.0. Five of these hemoglobins (I-V) were present in sufficient quantities for isolation by preparative isoelectric focusing and subsequent characterization. Cellulose acetate electrophoresis of the isolated hemoglobins resulted in producing as many as six different globin chains. The five hemoglobins were further characterized by their amino acid composition, N-terminal amino acid residue, and molecular weight.

Amino Acids↗
PubMed1977

The dissociation of transplantable tumors.

Four animal transplantable solid tumors, composed of varying morphologic architecture and intercellular specializations, were studied by light and electron microscopy. These tumors were dissociated into viable single cell populations using a combination of mechanical and enzymatic methods. The conditions necessary for optimal dissociation consisted of (a) preparation of the tumor to maximize the tissue surface area, (b) enzymatic digestion with continuous agitation and (c) additional agitation to release loosely attached cells. Other factors that influenced the dissociation were optimized and discussed.

Adenocarcinoma, Papillary↗