Columnar cell variant of papillary thyroid carcinoma. Report of a case with cytologic findings

BACKGROUND: The columnar and tall cell variants of papillary thyroid carcinoma (PTC) are uncommon variants and have generally been regarded as more aggressive forms in comparison to the more common classic papillary and follicular subtypes. Cytologic diagnosis of these rare variants is elusive since the characteristic nuclear features of the usual papillary thyroid carcinoma are very often absent or inconspicuous. We present a case of the columnar cell variant of PTC in a young woman that demonstrates the diagnostic challenge. CASE: A 24-year-old woman presented with a solitary, 3-cm mass in the left aspect of the thyroid. The aspirate consisted of a moderately cellular sampling of sheets, papillary clusters and microfollicles of cells with oval nuclei and uniform, finely granular chromatin. These cells were arranged in a peudostratified manner around well-defined fibrovascular cores. There were no intranuclear inclusions or well-defined nuclear grooves in the cells of the aspirate. There was also absence of colloid despite the presence of well-formed follicles. The resected thyroid revealed a columnar cell variant of PTC. CONCLUSION: The cytologic features of columnar cell-type PTC are at variance with those of classic PTC and are elusive in fine needle aspiration cytology. It is the lack of classic cytologic features of PTC that is distinctly apparent, yet it is the monomorphism of cells in the aspirate, their papillary configuration and their pseudostratification in well-formed fibrovascular cores that are the keys to the diagnosis. Immunohistochemical staining to rule out other thyroid neoplasms can be performed to aid in the diagnosis.     

L-Arginine inhibits xanthine oxidase-dependent endothelial dysfunction in hypercholesterolemia

Xanthine oxidase (XO)-derived superoxide contributes to endothelial dysfunction in humans and animal models of hypercholesterolemia (HC). Since L-arginine supplementation prevents defects in NO signaling, we tested the hypothesis that L-arginine blunts the inhibitory effect of XO on vascular function. Acetylcholine-mediated relaxation was significantly impaired in ring segments of HC rabbits, a response that was associated with an increase in plasma XO activity. L-Arginine treatment of HC rabbits reduced plasma XO and improved endothelial function. L-Arginine also modestly prolonged the lag time for oxidation in isolated lipoprotein samples. These results reveal that the principal action of L-arginine is to protect against the XO-dependent inactivation of NO in arteries of HC rabbits.     

PLD2 is enriched on exosomes and its activity is correlated to the release of exosomes

Exosomes are small vesicles secreted by different immune cells and which display anti-tumoral properties. Stimulation of RBL-2H3 cells with ionomycin triggered phospholipase D2 (PLD2) translocation from plasma membrane to intracellular compartments and the release of exosomes. Although exosomes carry the two isoforms of PLD, PLD2 was enriched and specifically sorted on exosomes when overexpressed in cells. PLD activity present on exosomes was clearly increased following PLD2 overexpression. PLD2 activity in cells was correlated to the amount of exosome released, as measured by FACS. Therefore, the present work indicates that exosomes can vehicle signaling enzymes.     

Identification of residues of the Caenorhabditis elegans LIN-1 ETS domain that are necessary for DNA binding and regulation of vulval cell fates

LIN-1 is an ETS domain protein. A receptor tyrosine kinase/Ras/mitogen-activated protein kinase signaling pathway regulates LIN-1 in the P6.p cell to induce the primary vulval cell fate during Caenorhabditis elegans development. We identified 23 lin-1 loss-of-function mutations by conducting several genetic screens. We characterized the molecular lesions in these lin-1 alleles and in several previously identified lin-1 alleles. Nine missense mutations and 10 nonsense mutations were identified. All of these lin-1 missense mutations affect highly conserved residues in the ETS domain. These missense mutations can be arranged in an allelic series; the strongest mutations eliminate most or all lin-1 functions, and the weakest mutation partially reduces lin-1 function. An electrophoretic mobility shift assay was used to demonstrate that purified LIN-1 protein has sequence-specific DNA-binding activity that required the core sequence GGAA. LIN-1 mutant proteins containing the missense substitutions had dramatically reduced DNA binding. These experiments identify eight highly conserved residues of the ETS domain that are necessary for DNA binding. The identification of multiple mutations that reduce the function of lin-1 as an inhibitor of the primary vulval cell fate and also reduce DNA binding suggest that DNA binding is essential for LIN-1 function in an animal.     

Delta12-Prostaglandin J2 inhibits the ubiquitin hydrolase UCH-L1 and elicits ubiquitin-protein aggregation without proteasome inhibition

To investigate molecular mechanisms linking inflammation with neurodegeneration, we treated neuronal cultures with prostaglandins (PGs), which are mediators of inflammation. PGA1, D2, J2, and Delta12-PGJ2, but not PGE2, reduced the viability and raised the levels of ubiquitinated proteins in the neuronal cells. PGJ2 and its metabolite, Delta12-PGJ2, were the most potent of the four neurotoxic PGs tested in inducing both effects. To address the mechanism by which these agents lead to the accumulation of ubiquitinated proteins, we tested their effects on neuronal ubiquitin hydrolases UCH-L1 and UCH-L3 as well as on proteasome activity. Notably, Delta12-PGJ2 inhibited the activities of UCH-L1 (K(i) approximately 3.5 microM) and UCH-L3 (K(i) approximately 8.1 microM) without affecting proteasome activity. Intracellular aggregates containing ubiquitinated proteins were detected in Delta12-PGJ2-treated cells, indicating that these aggregates can form independently of proteasome inhibition. In conclusion, impairment of ubiquitin hydrolase activity, such as triggered by Delta12-PGJ2, may be an important contributor to neurodegeneration associated with accumulation of ubiquitinated proteins and inflammation.     

Glycosaminoglycan disaccharide alters the dimer dissociation constant of the chemokine MIP-1 beta

Chemokines are immune system proteins that recruit and activate leukocytes to sites of infection. This recruitment is believed to involve the establishment of a chemokine concentration gradient by the binding of chemokines to glycosaminoglycans (GAGs). In previous studies, we elucidated the GAG binding site of the chemokine MIP-1beta and implicated the involvement of the chemokine dimer in GAG binding through residues across the dimer interface. In the present studies, nuclear magnetic resonance spectroscopy was used to investigate the effect of GAG binding on MIP-1beta dimerization. Using several dimerization-impaired variants of MIP-1beta (F13Y, F13L, L34W, and L34K), these studies indicate that the addition of disaccharide to the mutants increases their dimerization affinities. For MIP-1beta F13Y, the presence of the disaccharide increases the chemokine dimerization affinity about 9-fold as evidenced by a decrease in the dimer dissociation constant from 610 to 66 microM. Even more dramatically, the dimerization affinity of MIP-1beta L34W also increases upon addition of disaccharide, with the dimer dissociation constant decreasing from 97 to 6.5 microM. After this effect for the mutants of MIP-1beta was shown, similar experiments were conducted with the CC chemokine RANTES, and it was demonstrated that the presence of disaccharide increases its dimerization affinity by almost 7-fold. These findings provide further evidence of the importance of the dimer in chemokine function and provide the first quantitative investigation of the role of GAGs in the manipulation of the MIP-1beta quaternary structure.     

Mutations in the slow skeletal muscle fiber myosin heavy chain gene (MYH7) cause laing early-onset distal myopathy (MPD1)

We previously linked Laing-type early-onset autosomal dominant distal myopathy (MPD1) to a 22-cM region of chromosome 14. One candidate gene in the region, MYH7, which is mutated in cardiomyopathy and myosin storage myopathy, codes for the myosin heavy chain of type I skeletal muscle fibers and cardiac ventricles. We have identified five novel heterozygous mutations--Arg1500Pro, Lys1617del, Ala1663Pro, Leu1706Pro, and Lys1729del in exons 32, 34, 35, and 36 of MYH7--in six families with early-onset distal myopathy. All five mutations are predicted, by in silico analysis, to locally disrupt the ability of the myosin tail to form the coiled coil, which is its normal structure. These findings demonstrate that heterozygous mutations toward the 3' end of MYH7 cause Laing-type early-onset distal myopathy. MYH7 is the fourth distal-myopathy gene to have been identified.     

Immunofluorescence revealed the presence of NHE-1 in the nuclear membranes of rat cardiomyocytes and isolated nuclei of human, rabbit, and rat aortic and liver tissues

Using immunofluorescence and 3-dimensional confocal microscopy techniques, the present study was designed to verify if NHE-1 is present at the level of the nuclear membrane in cells that are known to express this type of exchanger. Nuclei were isolated from aortic tissues of adult human, rabbit, and rats, as well as from liver tissues of human fetus, and adult rabbit and rat. In addition, cultured ventricular cardiomyocytes were isolated from 2-week-old rat. Our results showed the presence of NHE-1 in isolated nuclei of aortic vascular smooth muscle and liver of human, rabbit, and rat. NHE-1 seems to be distributed throughout the isolated nucleus and more particularly at the level of the nuclear membranes. The relative fluorescence density of NHE-1 was significantly higher (p < 0.05) in isolated liver nuclei of human, when compared with those of rabbit and rat. However, in isolated nuclei of aortic vascular smooth muscle, the relative fluorescence density of NHE-1 was significantly (p < 0.001) higher in the rabbit when compared with human and rat. In cultured rat ventricular cardiomyocytes, NHE-1 fluorescent labeling could be easily seen throughout the cell, including the nucleus, and more particularly at both the sarcolemma and the nuclear membranes. In rat cardiomyocytes, the relative fluorescence density of NHE-1 of the sarcolemma membrane, including the cytosol, was significantly lower than that of the whole nucleus (including the nuclear envelope membranes). In conclusion, our results showed that NHE-1 is present at the nuclear membranes and in the nucleoplasm and its distribution and density may depend on cell type and species used. These results suggest that nuclear membranes' NHE-1 may play a role in the modulation of intranuclear pH.