Online audiovisual resources for learning the disinfection protocol for dental impressions: A critical analysis.

STATEMENT OF PROBLEM: Mainly because of poor training, substandard impression disinfection practices have been reported worldwide. PURPOSE: The purpose of this cross-sectional study was to assess the extension, usefulness, and reliability of contents on this topic available on the main video websites for self-training. MATERIAL AND METHODS: An analysis of the YouTube, Vimeo, and Dailymotion websites was undertaken in February 2018. The exclusion criteria were animal procedures, non-English language videos, advertisements, videos exclusively redirecting to websites, soundless videos, duplicated videos, and videos reporting on a research project. Information extension was assessed in 6 nonmutually exclusive dimensions, and usefulness was evaluated by using a 10-item scale. Reliability was assessed on a reliable or nonreliable basis. Statistical analyses were undertaken by using the Mann-Whitney and Fisher exact tests. RESULTS: Of 386 identified videos, only 22 met the selection criteria, mostly published by health-care professionals (n=8; 36.4%). Most videos had less than 3000 views. Median usefulness score: 3 (IR: 3-3; range: 0-6). No video included all 7 topics considered in the index (median 3; IR: 2.25-3; range: 0-4). Just 5 clips (22.7%) described a procedure according to the American Dental Association and Center for Disease Control (ADA and CDC) guidelines. CONCLUSIONS: Audiovisual online resources on dental impression disinfection includes incomplete information with limited usefulness and reliability. The number of views was not related to quality, and therefore, many viewers may be obtaining knowledge from substandard material.

Diffuse Cosmic Rays Shining in the Galactic Center: A Novel Interpretation of H.E.S.S. and Fermi-LAT γ-Ray Data.

We present a novel interpretation of the γ-ray diffuse emission measured by Fermi-LAT and H.E.S.S. in the Galactic center (GC) region and the Galactic ridge (GR). In the first part we perform a data-driven analysis based on PASS8 Fermi-LAT data: We extend down to a few GeV the spectra measured by H.E.S.S. and infer the primary cosmic-ray (CR) radial distribution between 0.1 and 3 TeV. In the second part we adopt a CR transport model based on a position-dependent diffusion coefficient. Such behavior reproduces the radial dependence of the CR spectral index recently inferred from the Fermi-LAT observations. We find that the bulk of the GR emission can be naturally explained by the interaction of the diffuse steady-state Galactic CR sea with the gas present in the central molecular zone. Although we confirm the presence of a residual radial-dependent emission associated with a central source, the relevance of the large-scale diffuse component prevents to claim a solid evidence of GC pevatrons.

Impact of hexavalent chromium on mammalian cell bioenergetics: phenotypic changes, molecular basis and potential relevance to chromate-induced lung cancer.

Occupational exposure to hexavalent chromium [Cr(VI)] has been firmly associated with the development of several pathologies, notably lung cancer. According to the current paradigm, the evolution of normal cells to a neoplastic state is accompanied by extensive metabolic reprogramming, namely at the level of energy-transducing processes. Thus, a complete understanding of the molecular basis of Cr(VI)-induced lung cancer must encompass the elucidation of the impact of Cr(VI) on metabolism. Research in this area is still in its infancy. Nonetheless, Cr(VI)-induced metabolic phenotypes are beginning to emerge. Specifically, it is now well documented that Cr(VI) exposure inhibits respiration and negatively affects the cellular energy status. Furthermore, preliminary results suggest that it also upregulates glucose uptake and lactic acid fermentation. From a mechanistic point of view, there is evidence that Cr(VI) exposure can interfere with energy transducing pathways at different levels, namely gene expression, intracellular protein levels and/or protein function. Loss of thiol redox control likely plays a key role in these processes. The transcriptional networks that control energy transduction can likewise be affected. Data also suggest that Cr(VI) exposure might compromise energy transducing processes through changes in the intracellular pools of their substrates. This article reviews, for the first time, the information available on Cr(VI) impact on mammalian cell bioenergetics. It aims to provide a framework for the understanding of the role played by bioenergetics in Cr(VI)-induced carcinogenesis and is also intended as a guide for future research efforts in this area.

Nutritional intake according to injury extent in ulcerative colitis patients.

BACKGROUND: Ulcerative colitis (UC) is often associated with nutritional deficiency, which appears to contribute to the progression of UC severity. The present study aimed to evaluate nutritional status and dietary intake in UC remission patients. METHODS: The present study comprised a cross-sectional study in which variables such as extent of disease (distal colitis, left-sided colitis, pancolitis), remission period, sex and age were recorded. Extent of disease was assessed by the results of a colonoscopy and dietary intake was evaluated by using 3-day, 24-h recalls. A Kruskall-Wallis test was used to compare the intake of macro- and micronutrients among the three study groups. The analysis was complemented by the Mann-Whitney test. A logistic regression analysis was performed to identify predictive factors of extent of disease (pancolitis versus left-sided colitis versus distal colitis). RESULTS: The median (range) age of the 59 patients was 49.0 (37.0-63.0) years and 53.3% were female. Twenty-six (44.1%) patients had distal colitis, 11 (18.6%) patients had left-sided colitis and 22 (37.3%) patients had pancolitis. A high probability of an inadequate intake of fibre (100%), fat soluble vitamins (>40% for vitamin A and >95% for vitamin E), vitamin C (>34%), calcium (>90%) and magnesium (>50%) was identified in the study group. Vitamin D intake (odds ratio = 0.60; 95% confidence interval = 0.39-0.94; P < 0.05) was significantly associated with increased intestinal damage. CONCLUSIONS: A large number of individuals showed an inadequate intake of nutrients. In addition, the consumption of vitamin D was significantly associated with extent of disease.

Human bronchial epithelial cells malignantly transformed by hexavalent chromium exhibit an aneuploid phenotype but no microsatellite instability.

Hexavalent chromium [Cr(VI)] is a well-recognized human lung carcinogen. In order to gain further insight into Cr(VI)-induced carcinogenesis, we have established an adequate in vitro cellular model for the study of this process. To this end, BEAS-2B cells were used. Chronic exposure of cells to 1 microM Cr(VI) induced changes in the cells' ploidy and a decrease in cloning efficiency, although cultures continued to progress to confluence. After prolonged exposure (12 passages), the culture became heterogeneous, exhibiting areas where apparently normal epithelial cells and morphologically altered cells coexisted. Subsequent culture at a very low density strongly accentuated the Cr(VI)-induced changes in morphology and pattern of growth. Three individual colonies were then ring-cloned and expanded into three subclonal aneuploid cell lines. These subclonal cell lines showed changes in growth pattern and morphology, as well as a karyotype drift concomitant with the overexpression of genes commonly involved in malignant transformation (c-MYC, EGFR, HIF-1alpha and LDH-A). Moreover, when one of these cell lines (RenG2) was injected into nude mice, it showed the ability to induce tumors. This cell line revealed no microsatellite instability (MSI), which points to the expression of a functional MLH1 protein and an active mismatch repair (MMR) system. Therefore, the progression to malignancy of the BEAS-2B cells involved Cr(VI)-induced transformants that retained the ability to repair DNA damage, suggesting that genotoxicity underlies the ongoing carcinogenic process.

Arginine butyrate downregulates p210 bcr-abl expression and induces apoptosis in chronic myelogenous leukemia cells.

Downregulation of bcr-abl expression in the chronic myelogenous leukemia cell line K562 using antisense oligonucleotides has been shown to enhance the sensitivity of the cells to apoptotic stimuli, suggesting that p210 bcr-abl, like bcl-2 functions as an anti-apoptosis factor (McGahon A et al, Blood 1994, 83: 1179). In these experiments, the inhibition of p210 bcr-abl expression alone was not sufficient to induce apoptosis. We demonstrated that exposure to low doses (0.5 mM) of a butyric acid analog, arginine butyrate, was capable of inducing apoptosis in selected leukemia cell lines, including K562 cells, and in fresh leukemia cells from patients with chronic myelogenous leukemia. To further explore the mechanisms of this effect, we examined expression of p210 bcr-abl after butyrate exposure and found a dose-related inhibition of p210 bcr-abl protein without concordant change in other phosphoproteins, including the JAK-1 kinase. Further analysis revealed that the inhibition of bcr-abl expression occurs due to transcriptional regulation of the bcr-abl gene by arginine butyrate. These results suggest that arginine butyrate and other butyrate analogs alone or in combination may be useful in the therapy of patients with chronic myelogenous leukemia or bcr-abl expressing acute leukemias.

Induction of apoptosis by cordycepin in ADA-inhibited TdT-positive leukemia cells.

The nucleoside analogue cordycepin (3'-deoxyadenosine), when protected against ADA deamination, is specifically cytotoxic for TdT-positive leukemia cells. Cordycepin-treated, ADA-inhibited, TdT-positive cells undergo the classic changes associated with drug-induced apoptosis: reduction in cell volume, chromatin clumping, membrane blebbing, and 180-bp multimer DNA laddering on agarose gels. In common with the apoptosis seen in normal TdT-positive thymocytes, following exposure to various agents, apoptosis induced by cordycepin in TdT-positive leukemia cells was associated with increased protein kinase A (PK-A) activity. Unlike thymocyte apoptosis however, no elevation in cAMP levels was seen preceding the rise in PK-A activity. Ex vivo we show that cordycepin monophosphate can activate PK-A as efficiently as cAMP. On this basis we speculate that cordycepin monophosphate in TdT-positive cells may be able to activate PK-A in place of cAMP, and that PK-A may phosphorylate TdT, augmenting its activity as an endonuclease. In cell-free experiments, the activity of recombinant TdT as an endonuclease digesting supercoiled plasmid DNA into linear fragments was dramatically increased following phosphorylation of TdT by PK-A. A role for TdT as an apoptotic endonuclease in TdT-positive leukemia cells following cordycepin exposure is now the subject of on-going work.

GDNF and RET-gene expression in anterior pituitary-cell types.

Glial cell line-derived neurotrophic factor (GDNF) is expressed in many neuronal and non-neuronal tissues during development as well as in adult animals. GDNF signaling is mediated through a two-component system consisting of the so called GDNF receptor-alfa (GFRalpha1) which binds to GDNF. Thereafter this complex binds to and activates the tyrosine kinase receptor RET. In this work, for the first time, we have characterized the expression of both GDNF and RET in the anterior pituitary. First of all, RT-PCR analysis, Western blot and immunohistochemistry of the whole anterior pituitary showed that GDNF, GFRalpha1 and RET are expressed in this gland. Following double-immunofluorescence of consecutive sections we found GDNF immunoreactivity in most cell types, and it was most abundant in corticotrophs (55%), LH (59%) and FSH-producing cells (81%). In contrast, while the majority of somatotrophs (87%) were stained for RET, no positive immunostaining could be detected in other cell types. Taken together, this data indicate that gonadotrophs and corticotrophs are the main source of GDNF synthesized in the anterior pituitary and that the somatotrophs appears to be their target cell. This study provides direct morphological evidences that GDNF may well be acting in a paracrine-like fashion in the regulation of somatotroph cell growth and/or cell function.

Corticocortical efferent systems in the monkey: a quantitative spatial analysis of the tangential distribution of cells of origin.

The laminar and tangential distributions of association neurons projecting from areas 4 and 6 of the frontal lobe to area 5 of the superior parietal lobule were studied in macaque monkeys by using horseradish peroxidase histochemistry. In both areas 4 and 6 association neurons were medium-large pyramidal cells of layers II and III, and pyramidal and fusiform cells of layers V-VI. Tangentially, they were distributed unevenly over the cortical surface occupying only certain parts of areas 4 and 6, including the dorsomedial part of area 6, the proximal arm region of Woolsey's M1 map, parts of the postarcuate cortex, and the supplementary motor area. Within these projection zones, the number of projection cells waxed and waned in a periodic fashion. Quantitative methods, including spectral analysis techniques, were used to characterize precisely spatial periodicities along the rostrocaudal dimension. The same quantitative analyses were used to determine the nature of the tangential distribution of corticocallosal cells of area 5 projecting to contralateral area 5. Both association and callosal spectra contained a strong component in the range of low spatial frequencies, corresponding to periods greater than 2 mm. Moreover, a consistent peak was observed in both spectra at spatial frequencies corresponding to periods ranging from 0.85 to 1.28 mm. This peak is in accord with the hypothesis of a modular organization of the cells of origin of these projection systems.

Immunohistochemical analysis of the immune reaction in the nervous system in paraneoplastic encephalomyelitis.

We examined frozen sections of frontal cortex, medulla, and dorsal root ganglia from a patient with small-cell lung cancer and paraneoplastic encephalomyelitis, involving the medulla and dorsal root ganglia, with a panel of antibodies reactive for IgG, IgM, C3, B cells, T cells, T cell subsets, macrophages, and class I and II (HLA-DR) major histocompatibility complex (MHC) antigens. We detected an antineuronal antibody (anti-Hu) in the serum and CSF of the patient and found deposits of IgG in the periphery of some neurons in dorsal root ganglia. The infiltrates were almost exclusively T cells with a predominance of CD8-positive cells. Neurons did not express class I or II MHC antigens. Satellite cells in the dorsal root ganglia from the patient and controls were HLA-DR-positive. These data indicate that CD8-positive T cells predominate in the inflammatory infiltrates of paraneoplastic encephalomyelitis. IgG deposits may be relevant in the damage of the sensory neurons.

Pyramidal input to the intracerebellar nuclei of the cat.

In unanesthetized cats it has been found that pyramidal volleys elicited upon medullary pyramidal tract stimulation were capable of modifying the discharge of 41% of intracerebellar nuclear cells, via pontocerebellar systems impinging predominantly on the lateral cerebellar cortex. The incidence of responsive cells was 80% in the dentate nucleus compared with 10% in the fastigial nucleus, 11% in the anterior and 12% in the posterior division of the interpositus nucleus. The response was in 59% of the cases excitation followed by inhibition, in 30% of the cases a pure excitation and in 11% of the cases a pure inhibition. Excitation, pure or followed by inhibition, had a mean latency of 5.78 ms and a mean duration of 12.21 ms, while inhibition displayed a mean latency of 9.03 ms and a mean duration of 34.64 ms. The possible functional significance of the pyramidal input to the lateral cerebellum is briefly discussed in relation to a possible convergence of pyramidal and associative impulses in single cerebellar neurons.

Interpositus nucleus influences on pyramidal tract neurons in the cat.

The influences of the interpositus nucleus on pyramidal tract neurons were investigated by stimulating, in unanesthetized cats, interpositus nucleus foci which activated single muscles in limbs, while recording unitary discharges of pyramidal tract neurons located in foci (area 4 gamma) from which contraction was obtained in the same muscles as those excited from interpositus nucleus (agonist pyramidal tract neurons), in their antagonist (antagonist pyramidal tract neurons), or in heteronymous muscles (heteronymous pyramidal tract neurons). It was found that agonist pyramidal tract neurons were inhibited from the interpositus nucleus, whereas antagonist pyramidal tract neurons displayed a pure excitatory or an excitatory-inhibitory pattern, and the heteronymous neurons were not significantly influenced. A direct activation of interposito-thalamic efferents could be responsible for these effects. In fact, unitary discharge changes of pyramidal tract neurons, elicited from interpositus nucleus stimulation, persisted after chronic intermediate cortex ablation and dentate nucleus lesions, and disappeared following coagulations in the ventrolateral nucleus of the thalamus. These results suggest that interpositus nucleus efferents, which activate a given muscle, via the rubrospinal pathway, could inhibit the discharge of pyramidal neurons controlling that muscle, via collaterals direct to the thalamic ventrolateral nucleus.

Human cortical activity related to unilateral movements. A high resolution EEG study.

In the present study a modern high resolution electroencephalography (EEG) technique was used to investigate the dynamic functional topography of human cortical activity related to simple unilateral internally triggered finger movements. The sensorimotor area (M1-S1) contralateral to the movement as well as the supplementary motor area (SMA) and to a lesser extent the ipsilateral M1-S1 were active during the preparation and execution of these movements. These findings suggest that both hemispheres may cooperate in both planning and production of simple unilateral volitional acts.

Topography of spatially enhanced human short-latency somatosensory evoked potentials.

In the present study modern high resolution electroencephalography (EEG) was used to spatially enhance human median nerve short-latency somatosensory evoked potentials (SEPs). It was shown that the spatially enhanced N30 consisted of two frontal subcomponents, one located in the frontal-lateral area of the scalp, the other located in the frontal-mesial area. Both of these subcomponents were most reduced in amplitude (or disappeared) during concomitant hand movement ipsilateral to the stimulus, but were differentially influenced by executed contralateral movement and imagined ipsilateral movement. These results support the hypothesis of an involvement of the frontal-mesial cortex (including the supplementary motor area) in the generation of the frontal N30.

Human short latency cortical responses to somatosensory stimulation. A high resolution EEG study.

Human short-latency cortical responses to median nerve stimulation were investigated with a new high resolution electroencephalography technology that markedly enhanced spatial details of somatosensory-evoked potentials (SEPs). Maximum amplitude potentials were estimated over contralateral and/or frontal-mesial scalp regions about 20, 22, 24, 26, 30, 32 and 45 ms following the stimulation. Frontal-lateral P20-N24-N30-P45 and parietal-lateral N20-P24-P30-N45 showed dipolar patterns, whereas frontal-mesial N24-N30-P45 and central-lateral P22-N26-N32-P45 presented no clearcut dipole counterpart. Plausibly, the spatially enhanced frontal-parietal SEP components were generated (tangential dipoles) within the lateral central sulcus cortex, and anticipated the central-lateral and frontal-mesial components generated (radial dipoles) from the crown of the pre- and/or post-central gyri and the supplementary motor area, respectively.

Callosal and association neurons in the cortical space: a spectral analysis approach.

The tangential distributions of callosal neurons of area 5 projecting homotopically to the contralateral hemisphere and of association neurons of areas 4 and 6 projecting to ipsilateral area 5 were determined in the macaque monkey by using neuroanatomical methods based on the retrograde transport of horseradish peroxidase. Both distributions were studied qualitatively through 2-dimensional reconstructions of the cortical areas of origin and quantitatively through a spectral analysis. This approach facilitated the characterization of the spatial periodicities contained in these distributions revealing that, in area 5, callosal neurons were organized in bands of various shapes and width; these bands were composed of more discrete clusters of cells. In the frontal lobe, association neurons projecting to ipsilateral area 5 were arranged similarly. This study suggests that a common principle underlies the tangential organization of both callosal and association projecting cells in different cortical areas and emphasizes a basic similarity of interhemispheric and intrahemispheric connections.

"Gating" of human short-latency somatosensory evoked cortical responses during execution of movement. A high resolution electroencephalography study.

The present study aimed at investigating gating of median nerve somatosensory evoked cortical responses (SECRs), estimated during executed continuous complex ipsilateral and contralateral sequential finger movements. SECRs were modeled with an advanced high resolution electroencephalography technology that dramatically improved spatial details of the scalp recorded somatosensory evoked potentials. Integration with magnetic resonance brain images allowed us to localize different SECRs within cortical areas. The working hypothesis was that the gating effects were time varying and could differently influence SECRs. Maximum statistically significant (p<0. 01) time-varying gating (magnitude reduction) of the short-latency SECRs modeled in the contralateral primary motor and somatosensory and supplementary motor areas was computed during the executed ipsilateral movement. The gating effects were stronger on the modeled SECRs peaking 30-45 ms (N30-P30, N32, P45-N45) than 20-26 ms (P20-N20, P22, N26) post-stimulus. Furthermore, the modeled SECRs peaking 30 ms post-stimulus (N30-P30) were significantly increased in magnitude during the executed contralateral movement. These results may delineate a distributed cortical sensorimotor system responsible for the gating effects on SECRs. This system would be able to modulate activity of SECR generators, based on the integration of afferent somatosensory inputs from the stimulated nerve with outputs related to the movement execution.

Pyramidal influences on ventral thalamic nuclei in the cat.

In pericruciate cortex-ablated 'pyramidal cats', discharge changes in single neurons of ventral thalamic nuclei were studied, following stimulation of ipsilateral medullary (MPT) and contralateral cervical (CPT) pyramidal tract. It was seen that cells in ventrolateral nucleus, ventroanterior nucleus and ventromedial nucleus were not significantly (2.2%) modified by impulses coming from MPT and CPT. Conversely, a very high percentage (58.8%) of cells in ventrobasal complex (VB) responded to MPT stimulation (64.4% in ventroposterolateral nucleus, VPL, and 40.7% in ventroposteromedial nucleus, VPM). A considerable number (34.8%) of VPL cells responsive to MPT, were influenced by CPT, while none of the cells in VPM were. The most frequent effect observed in VB neurons, on MPT and CPT stimulation, was excitation followed by depression of discharge.