Cytologic features of metastatic papillary thyroid carcinoma in cervical lymph nodes

OBJECTIVE: To elucidate the cytologic characteristics of metastatic papillary thyroid carcinoma (PTC) in cervical lymph nodes and the differences in cervical lymph nodes from those of stage I (intrathyroidal) PTC. STUDY DESIGN: Forty-seven cases of papillary thyroid carcinoma with cervical lymph node metastasis (group A) and 38 cases of intrathyroidal papillary carcinoma (group B) were included in this study. Preoperative fine needle aspiration cytology (FNAC) examination was performed on enlarged cervical lymph nodes (47 cases, group A) and enlarged thyroid nodules (13 cases, group A, and 38 cases, group B). All the cases were surgically excised and pathologically verified. The cytologic smears were reviewed and analyzed. RESULTS: The cytologic characteristics of metastatic PTC in cervical lymph nodes displayed a higher frequency of foamy macrophages (51.1% vs. 26.3%) and a lower frequency of distinct cell borders (38.3% vs. 71.1%) than those of stage I PTC. Metastatic PTC in cervical lymph nodes also had a higher frequency of cystic degeneration (44.7% vs. 5.3%) than intrathyroidal lesions. In 1 of the 47 cases with lymph node metastasis, the aspirate contained macrophages but no tumor cells. CONCLUSION: FNAC was useful in the diagnosis of metastatic PTC in cervical lymph nodes. However, because cystic degeneration appeared frequently, FNAC combined with thyroid ultrasonography to find the primary lesion is necessary in this situation.     

An overexpression screen in Drosophila for genes that restrict growth or cell-cycle progression in the developing eye

We screened for genes that, when overexpressed in the proliferating cells of the eye imaginal disc, result in a reduction in the size of the adult eye. After crossing the collection of 2296 EP lines to the ey-GAL4 driver, we identified 46 lines, corresponding to insertions in 32 different loci, that elicited a small eye phenotype. These lines were classified further by testing for an effect in postmitotic cells using the sev-GAL4 driver, by testing for an effect in the wing using en-GAL4, and by testing for the ability of overexpression of cycE to rescue the small eye phenotype. EP lines identified in the screen encompass known regulators of eye development including hh and dpp, known genes that have not been studied previously with respect to eye development, as well as 19 novel ORFs. Lines with insertions near INCENP, elB, and CG11518 were characterized in more detail with respect to changes in growth, cell-cycle phasing, and doubling times that were elicited by overexpression. RNAi-induced phenotypes were also analyzed in SL2 cells. Thus overexpression screens can be combined with RNAi experiments to identify and characterize new regulators of growth and cell proliferation.     

Rhodostomin,a disintegrin,inhibits adhesion of neutrophils to fibrinogen and attenuates superoxide production

Disintegrins are a group of Arg (or Lys)-Gly-Asp-containing snake venom proteins which inhibit platelet aggregation via the blockade of _llb3 integrin. Here, we studied the effect of rhodostomin, a disintegrin purified from the venom ofCalloselasma rhodostoma, on the functions of neutrophils. By flow cytometric analysis of whole blood, we found that rhodostomin interacted with leukocytes of the myeloid and monocytic lineage as well as with platelets. The binding of rhodostomin to neutrophils could reach saturation in a dose-dependent manner, and its binding was increased in neutrophils stimulated with phorbol 12-myristate 13-acetate (PMA) and N-formyl-Met-Leu-Phe. EDTA did not inhibit the binding of rhodostomin. In addition, bound rhodostomin was not internalized. Soluble fibrinogen, a natural ligand of Mac-1 (CD11b/CD18, _M2), and the peptide, GRGDS, inhibited the binding of rhodostomin to PMA-activated neutrophils, while 7E3, a monoclonal antibody (mAb) raised against ₃ integrin, or mAbs raised against _M and ₂ integrin did not. Rhodostomin blocked the Mac-1-dependent adhesion of neutrophils to immobilized fibrinogen, in parallel with decreasing the production of superoxide from adherent neutrophils. Taken together, our results indicate that rhodostomin binds to activated neutrophils in an RGD-dependent manner, blocks the adhesion of activated neutrophils to fibrinogen and attenuates superoxide production, suggesting that rhodostomin may have anti-inflammatory properties.     

Screening marine algae from China for their antitumor activities

Thirty-nine species of marine algae collected from the coast of China were screened for their antitumor activities, and eight species Leathesia difformes, Polysiphonia urcedata, Scytosiphon lomentarius, Gloiopeliis furcata, Punctaria latifolia, Symphyocladia latiuscula, Rhodomela confervoides and Ulva pertusa showed potent cytotoxic activities. Three, Rhodomela confervoides, Scytosiphon lomentarius and Gloiopeliis furcata, were used for further investigation. More than 30 compounds were isolated and purified, and 14 bromophenols, 1 steroid and 1 carotene were identified by advanced spectroscopic methods including IR, MS, and NMR techniques. Amongst the 16 identified compounds, 7 showed vigorously selective activities against KB, Bel7402 and A549 cancer cells, and 6 bromophenols were new compounds.     

Aberrant Cdk5 activation by p25 triggers pathological events leading to neurodegeneration and neurofibrillary tangles

Cyclin-dependent kinase 5 (Cdk5) and its regulatory subunit p35 are integral players in the proper development of the mammalian central nervous system. Proteolytic cleavage of p35 generates p25, leading to aberrant Cdk5 activation. The accumulation of p25 is implicated in several neurodegenerative diseases. In primary neurons, p25 causes apoptosis and tau hyperphosphorylation. Current mouse models expressing p25, however, fail to rigorously recapitulate these phenotypes in vivo. Here, we generated inducible transgenic mouse lines overexpressing p25 in the postnatal forebrain. Induction of p25 preferentially directed Cdk5 to pathological substrates. These animals exhibited neuronal loss in the cortex and hippocampus, accompanied by forebrain atrophy, astrogliosis, and caspase-3 activation. Endogenous tau was hyperphosphorylated at many epitopes, aggregated tau accumulated, and neurofibrillary pathology developed progressively in these animals. Our cumulative findings provide compelling evidence that in vivo deregulation of Cdk5 by p25 plays a causative role in neurodegeneration and the development of neurofibrillary pathology.     

Calcium plays a critical role in determining the acetylcholine receptor-clustering activities of alternatively spliced isoforms of Agrin

Neural agrin, an extracellular matrix protein secreted by motor neurons, plays a key role in clustering of nicotinic acetylcholine receptors (AChR) on postsynaptic membranes of the neuromuscular junction. The action of agrin is critically dependent on an eight-amino acid insert (z8 insert) in the third of three consecutive laminin-like globular (G3) domains near the C terminus of neural agrin. Alternatively spliced agrin isoforms in non-neural tissue including muscle lack the z8 insert and are biologically inactive. Extracellular calcium has been shown to be imperative for the AChR-clustering activity of neural agrin. It is unclear, however, whether calcium preferentially interacts with the neural isoform or whether it acts solely as an intracellular messenger that mediates agrin signaling. Here, we report the G3 domain of rat neural agrin (AgG3z8) expressed in Pichia pastoris promoted AChR clustering on surface of C2C12 myotubes in a calcium-dependent manner. Direct binding of calcium to AgG3z8 was demonstrated by trypsin digestion and thermal denaturation experiments. Moreover, calcium induced a significant change in the conformation of AgG3z8, and the effect was correlated with an enhanced binding affinity of the protein to muscle receptor. Mutation of calcium-binding residues in the G3 domain diminished the conformational change of neural agrin, reduced its binding affinity to muscle membrane, and inhibited AChR-clustering activity. Conversely, the G3 domain of muscle agrin (AgG3z0) displayed little structural change in the presence of calcium, bound poorly to muscle surface, and was inactive in AChR-clustering assays. We conclude that distinct interactions of the G3 domain with calcium determine the biological activities of alternatively spliced agrin isoforms during synapse formation.