Beyond the suspicious thyroid fine needle aspirate. A review

Fine needle aspiration (FNA) is currently the best diagnostic tool for thyroid nodules. However, the cytologic category of indeterminate or suspicious lesion, which is found in 10-15% of cases, remains a challenge. Since neither clinical presentation nor intraoperative frozen section is often helpful in differentiating these lesions and since surgical procedures for benign and malignant lesions differ, there is a clear need to develop ancillary tests. In this review we identify 12 potential markers of thyroid malignancy that have been examined in thyroid cytologic samples. Although many of these markers hold promise as adjuncts to FNA cytology, multicenter studies have often shown limitations in the predictive value of these assays due to lack of specificity, sensitivity or both. The recent development, however, of tissue microarray techniques to validate promising new markers suggests that improvements in the approach to indeterminate thyroid FNA samples may soon be at hand. This review presents a summary of the issues facing the development of a clinically useful diagnostic test in the differential diagnosis of thyroid nodules.     

Effect of hypothermia on brain multi-parametric activities in normoxic and partially ischemic rats

Hypothermia, as well as anesthesia, are known to protect the brain against ischemia, hypoxia and other pathological damages. One of the mechanisms of this improvement could be by lowering brain function, and thereby lowering oxygen demand. We examined the effect of hypothermia on brain function and blood supply in awake and anesthetized rats and studied the interaction between partial ischemia and the responses to hypothermia. The brain function multiprobe (BFM) used enabled simultaneous measurements of cerebral blood flow (CBF), mitochondrial NADH redox state, extracellular K(+) concentration, DC potential and ECoG from the cerebral cortex in rats whose brain temperature was lowered by 5 degrees C. Hypothermia was induced in awake, anesthetized and brain ischemic-anesthetized rats. In anesthetized and ischemic-anesthetized rats, the time required for lowering the brain temperature by 5 degrees C was five times less than in the normal awake animals. No significant changes in CBF and NADH levels were found in response to hypothermia in the awake animals. In contrast, a significant decrease in extracellular K(+) concentration was recorded under hypothermia, probably due to the lower rate of depolarization. Hypothermia in anesthetized and in ischemic-anesthetized rats did not significantly affect the levels of mitochondrial NADH, CBF and extracellular K(+). Hypothermia under ischemia was expected to be more effective.     

Effective stimuli for constructing reliable neuron models

The rich dynamical nature of neurons poses major conceptual and technical challenges for unraveling their nonlinear membrane properties. Traditionally, various current waveforms have been injected at the soma to probe neuron dynamics, but the rationale for selecting specific stimuli has never been rigorously justified. The present experimental and theoretical study proposes a novel framework, inspired by learning theory, for objectively selecting the stimuli that best unravel the neuron's dynamics. The efficacy of stimuli is assessed in terms of their ability to constrain the parameter space of biophysically detailed conductance-based models that faithfully replicate the neuron's dynamics as attested by their ability to generalize well to the neuron's response to novel experimental stimuli. We used this framework to evaluate a variety of stimuli in different types of cortical neurons, ages and animals. Despite their simplicity, a set of stimuli consisting of step and ramp current pulses outperforms synaptic-like noisy stimuli in revealing the dynamics of these neurons. The general framework that we propose paves a new way for defining, evaluating and standardizing effective electrical probing of neurons and will thus lay the foundation for a much deeper understanding of the electrical nature of these highly sophisticated and non-linear devices and of the neuronal networks that they compose.     

Rac-dependent doubling of HeLa cell area and impairment of cell migration and cell cycle by compounds from Iris germanica

Plants are an infinite source of bioactive compounds. We screened the Israeli flora for compounds that interfere with the organization of the actin cytoskeleton. We found an activity in lipidic extract from Iris germanica that was able to increase HeLa cell area and adhesion and augment the formation of actin stress fibers. This effect was not observed when Ref52 fibroblasts were tested and was not the result of disruption of microtubules. Further, the increase in cell area was Rac1-dependent, and the iris extract led to slight Rac activation. Inhibitor of RhoA kinase did not interfere with the ability of the iris extract to increase HeLa cell area. The increase in HeLa cell area in the presence of iris extract was accompanied by impairment of cell migration and arrest of the cell cycle at G1 although the involvement of Rac1 in these processes is not clear. Biochemical verification of the extract based on activity-mediated fractionation and nuclear magnetic resonance analysis revealed that the active compounds belong to the group of iridals, a known group of triterpenoid. Purified iripallidal was able to increase cell area of both HeLa and SW480 cells.     

Muscle-bound primordial stem cells give rise to myofiber-associated myogenic and non-myogenic progenitors

Myofiber cultures give rise to myogenic as well as to non-myogenic cells. Whether these myofiber-associated non-myogenic cells develop from resident stem cells that possess mesenchymal plasticity or from other stem cells such as mesenchymal stem cells (MSCs) remain unsolved. To address this question, we applied a method for reconstructing cell lineage trees from somatic mutations to MSCs and myogenic and non-myogenic cells from individual myofibers that were cultured at clonal density.Our analyses show that (i) in addition to myogenic progenitors, myofibers also harbor non-myogenic progenitors of a distinct, yet close, lineage; (ii) myofiber-associated non-myogenic and myogenic cells share the same muscle-bound primordial stem cells of a lineage distinct from bone marrow MSCs; (iii) these muscle-bound primordial stem-cells first part to individual muscles and then differentiate into myogenic and non-myogenic stem cells.     

Type 1 diabetes affects topoisomerase I activity and GlcNAcylation in rat organs: kidney, liver and pancreas

Chronic hyperglycemia leads to the development of diabetes-induced organ complications, through changes in gene expression and protein function. We previously showed that in cell lines, topoisomerase I (topo I) is modified by O-GlcNAcylation, which affects its DNA relaxation activity. Since topo I participates in gene expression processes, we assumed that high glucose levels will affect its regulation and activity. Here we examined the effect of hyperglycemia on the regulation, GlcNAcylation and activity of topo I, in various internal rat organs that were subjected to diabetes-induced complications. Type 1 diabetes was induced in female rats by Streptozotocin injection. Topo I activity in nuclear protein extracts derived from diabetic and nondiabetic rat organs and topo I mRNA level were examined. Topo I and O-linked beta-N-acetylglucosamine (O-GlcNAc) transferase proteins and their O-GlcNAcylation were determined by western blot and immunoprecipitation assays. We show that topo I activity and enzyme protein level decreased in various tissues derived from the diabetic animals, whereas the enzyme mRNA level was not altered. Topo I protein was modified in vivo by O-GlcNAc, and O-GlcNAc transferase was coprecipitated with topo I protein, suggesting a possible interaction between both enzymes. This study demonstrates, for the first time, that topo I activity is regulated by high glucose levels, as a result of the diabetic state and is modified in vivo by O-GlcNAcylation, suggesting that topo I, an essential enzyme for gene expression, is involved in cellular processes which may lead to the pathogenesis of diabetic complications.     

Hijacking leucyl-tRNA synthetase for amino acid-dependent regulation of TORC1

TORC1 activity in all eukaryotes is dependent on amino acid availability. However, the mechanism through which TORC1 senses amino acids is still a mystery. In the current issues of Molecular Cell and Cell, Bonfils et?al. (2012) and Han et?al. (2012) implicate leucyl-tRNA synthetase in this evolving story.     

Tyrosine phosphorylation of measles virus nucleocapsid protein in persistently infected neuroblastoma cells.

Subacute sclerosing panencephalitis is a slowly progressing fatal human disease of the central nervous system which is a delayed sequel of measles virus (MV) infection. A typical pathological feature of this disease is the presence of viral ribonucleocapsid structures in the form of inclusion bodies and the absence of infectious virus or budding viral particles. The mechanisms governing the establishment and maintenance of a persistent MV infection in brain cells are still largely unknown. To understand the mechanisms underlying MV persistence in neuronal cells, a tissue culture model was studied. Clone NS20Y/MS of the murine neuroblastoma C1300 persistently infected with the wild-type Edmonston strain of MV secretes relatively high levels of alpha/beta interferon (IFN). As shown previously, treatment of the persistently infected cultures with anti-IFN serum converted the persistent state into a productive infection indicated by the appearance of multinucleated giant cells. In this study, we have investigated whether alpha/beta IFN produced by NS20Y/MS cells activates cellular protein tyrosine kinases which will induce tyrosine phosphorylating activity specific to virus-infected cells. We present data to show augmented protein tyrosine kinase activity in the persistently infected cells. We demonstrate that the MV N protein is phosphorylated on tyrosine in addition to serine and threonine in the persistent state but not in NS20Y cells acutely infected with MV.