Revealing the Complex Nature of Bonding in the Binary High-Pressure Compound FeO_{2}

Extreme pressures and temperatures are known to drastically affect the chemistry of iron oxides, resulting in numerous compounds forming homologous series nFeOmFe_{2}O_{3} and the appearance of FeO_{2}. Here, based on the results of in situ single-crystal x-ray diffraction, Mössbauer spectroscopy, x-ray absorption spectroscopy, and density-functional theory+dynamical mean-field theory calculations, we demonstrate that iron in high-pressure cubic FeO_{2} and isostructural FeO_{2}H_{0.5} is ferric (Fe^{3+}), and oxygen has a formal valence less than 2. Reduction of oxygen valence from 2, common for oxides, down to 1.5 can be explained by a formation of a localized hole at oxygen sites.

Changes in Heart Rate Variability During Heartfulness Meditation: A Power Spectral Analysis Including the Residual Spectrum

Background: Meditation refers to a group of practices commonly proposed to treat stress-related conditions and improve overall wellness. In particular, meditation might exert beneficial actions on heart rate variability (HRV) by acting on autonomic tone with an increase in the vagal activity. The effects of heartfulness meditation (HM) on HRV remain poorly defined.

Methods: We investigated the effects of HM on HRV in a group of 26 healthy subjects. Subjects were regularly practicing this form of meditation on a daily basis. We assessed the HRV and residual HRV (rHRV) at rest and during meditation. We also used as control a period of respiratory rhythm imposed by an auditory signal, with the imposed breathing rhythm being identical to the spontaneous rhythm recorded during meditation.

Results: During deep meditation period, the standard deviation of RR intervals (SD_RR), coefficient of variation of RR intervals (CV_RR), and total power (TP) were decreased while the low-frequency power (LFP), normalized LFP (nLFP), and normalized residual LFP (nrLFP) were increased as compared with those at rest, suggesting that the global vagal modulation was suppressed while the baroreflex was increased during deep medication. At the end of meditation, the LFP, residual LFP (rLFP), nLFP, nrLFP, low-/high-frequency power ratio (LHR), and residual LHR (rLHR) were increased while the residual very low-frequency power (rVLFP), normalized high-frequency power (nHFP), and normalized residual HFP (nrHFP) were decreased, as compared with those during paced breathing, suggesting that the vagal modulation was decreased while the sympathetic modulation was increased by deep meditation. During paced breathing period, the SD_RR, CV_RR, TP, LFP, rLFP, nLFP, nrLFP, LHR, and rLHR were decreased while nHFP and nrHFP were increased as compared with at rest, suggesting that paced breathing could suppress the sympathetic modulation and enhance the vagal modulation.

Conclusion: HM can induce a suppression of global vagal modulation and increased the sympathetic modulation and baroreflex. In addition, paced breathing can suppress the sympathetic modulation and enhance the vagal modulation. Unlike studies using other types of meditation, we did not identify evidence of increased vagal tone during HM.

Effect of hepatitis B virus on steatosis in hepatitis C virus co-infected subjects: A multi-centre study and systematic review

It remains unclear whether hepatitis B virus (HBV) infection may modify the severity of viral steatosis in patients coinfected with chronic hepatitis C virus (HCV). We examined the influence of coinfection with HBV on prevalence of steatosis in chronic hepatitis C in a multi-centre cohort of HBV-HCV subjects, and by performing a systematic review and meta-analysis of the literature. We centrally and blindly assessed steatosis prevalence and severity in a cohort of HBV-HCV coinfected subjects compared to HCV and HBV monoinfected controls and we performed a systematic review of studies addressing the prevalence of steatosis in HBV-HCV subjects compared to HCV controls. In the clinical cohort, we included 85 HBV-HCV, 69 HBV and 112 HCV subjects from 16 international centres. There was no significant difference in steatosis prevalence between the HBV-HCV and the HCV groups (33% vs 45%, P = .11). In subgroup analysis, lean HBV-HCV subjects with detectable HBV DNA had less steatosis than lean HCV subjects matched for HCV viremia (15% vs 45%, P = .02). Our literature search identified 5 additional studies included in a systematic review. Overall, prevalence of steatosis > 5% was similar in HBV-HCV infection compared to HCV (pooled odds ratio [OR] 0.91, 95% CI 0.53-1.6) although there was significant heterogeneity (I² 69%, P = .007). In conclusion, although the prevalence of steatosis is similar in HBV-HCV compared to HCV subjects, our analysis suggests that there may be an inhibitory effect of HCV-induced steatogenesis by HBV in certain subgroups of patients.

A Pilot Study on the Effects of Transcranial Direct Current Stimulation on Brain Rhythms and Entropy during Self-Paced Finger Movement using the Epoc Helmet

Transcranial direct current stimulation (tDCS) of the cerebellum is emerging as a novel non-invasive tool to modulate the activity of the cerebellar circuitry. In a single blinded study, we applied anodal tDCS (atDCS) of the cerebellum to assess its effects on brain entropy and brain rhythms during self-paced sequential finger movements in a group of healthy volunteers. Although wearable electroencephalogram (EEG) systems cannot compete with traditional clinical/laboratory set-ups in terms of accuracy and channel density, they have now reached a sufficient maturity to envision daily life applications. Therefore, the EEG was recorded with a comfortable and easy to wear 14 channels wireless helmet (Epoc headset; electrode location was based on the 10-20 system). Cerebellar neurostimulation modified brain rhythmicity with a decrease in the delta band (electrode F3 and T8, p < 0.05). By contrast, our study did not show any significant change in entropy ratios and laterality coefficients (LC) after atDCS of the cerebellum in the 14 channels. The cerebellum is heavily connected with the cerebral cortex including the frontal lobes and parietal lobes via the cerebello-thalamo-cortical pathway. We propose that the effects of anodal stimulation of the cerebellar cortex upon cerebral cortical rhythms are mediated by this key-pathway. Additional studies using high-density EEG recordings and behavioral correlates are now required to confirm our findings, especially given the limited coverage of Epoc headset.

Trains of electrical stimulation of the trapezius muscles redistribute the frequencies of body oscillations during stance

We investigated the postural effects of trains of electrical stimulation (TES) applied unilaterally or bilaterally on the trapezius muscle in 20 healthy subjects (mean age: 23.1 ± 1.33 years; F/M: 8/12). The anterior-posterior (AP) displacements (AP axis), medio-lateral displacements (ML axis) and total travelled distances (TTW) of the centre of pressure (COP) remained unchanged with TES. However, detailed spectral analysis of COP oscillations revealed a marked decrease of the magnitudes of peak power spectral density (peak PSD) following application of TES. Peak PSD was highly correlated with the intensity of stimulation (P < 0.001 both the AP and ML axes). For the AP axis, the integrals of the sub-bands 0-0.4, 0.4-1.5, 1.5-3 Hz were significantly decreased (P < 0.001), the integrals of the sub-bands 3-5 and 5-8 Hz were not significantly affected (P>0.30) and the integrals of the sub-band 8-10 Hz were significantly increased (P < 0.001). The ratios of the integrals of sub-bands 8-10 Hz/0-3 Hz were markedly enhanced with bilateral TES (P < 0.001). For the ML axis, the effects were striking (P < 0.001) for the sub-bands 0-0.4, 0.4-1.5 and 8-10 Hz. For both the AP and ML axes, a significant inverse linear relationship was found between the intensity of TES and the average speed of COP. We show that TES applied over the trapezius muscles exerts significant and so far unrecognised effects upon oscillations of the COP, decreasing low-frequency oscillations and enhancing high-frequency oscillations. Our data unravel a novel property of the trapezius muscles upon postural control. We suggest that this muscle plays a role of a distributor of low-frequency versus high-frequency sub-bands of frequency during stance. Previous studies have shown that patients with supra-tentorial stroke show an increased peak PSD in low frequencies of body oscillations. Therefore, our findings provide a rationale to assess neurostimulation of the trapezius muscle in the rehabilitation of postural deficits in supra-tentorial stroke.

Guidelines for presymptomatic testing for Huntington's disease: past, present and future in France

Huntington's disease was the first adult onset neurological disease for which presymptomatic genetic testing became possible. It served as a model for the approach which constituted a radical change in medical practice and provided an important framework for multi-step, multidisciplinary, counselling for at risk persons. We will review the historical context of guidelines and good clinical practices, the experiences of our team which covers more than 20 years of presymptomatic testing for Huntington's disease in France, and explore the impact of the new French legislation for the future of presymptomatic testing of diseases for which neither preventive measures nor curative treatments are yet available.

Accuracy of genomic selection models in a large population of open-pollinated families in white spruce

Genomic selection (GS) is of interest in breeding because of its potential for predicting the genetic value of individuals and increasing genetic gains per unit of time. To date, very few studies have reported empirical results of GS potential in the context of large population sizes and long breeding cycles such as for boreal trees. In this study, we assessed the effectiveness of marker-aided selection in an undomesticated white spruce (Picea glauca (Moench) Voss) population of large effective size using a GS approach. A discovery population of 1694 trees representative of 214 open-pollinated families from 43 natural populations was phenotyped for 12 wood and growth traits and genotyped for 6385 single-nucleotide polymorphisms (SNPs) mined in 2660 gene sequences. GS models were built to predict estimated breeding values using all the available SNPs or SNP subsets of the largest absolute effects, and they were validated using various cross-validation schemes. The accuracy of genomic estimated breeding values (GEBVs) varied from 0.327 to 0.435 when the training and the validation data sets shared half-sibs that were on average 90% of the accuracies achieved through traditionally estimated breeding values. The trend was also the same for validation across sites. As expected, the accuracy of GEBVs obtained after cross-validation with individuals of unknown relatedness was lower with about half of the accuracy achieved when half-sibs were present. We showed that with the marker densities used in the current study, predictions with low to moderate accuracy could be obtained within a large undomesticated population of related individuals, potentially resulting in larger gains per unit of time with GS than with the traditional approach.

IL28B polymorphisms, IP-10 and viral load predict virological response to therapy in chronic hepatitis C

BACKGROUND

Hepatitis C virus (HCV) is a major cause of chronic liver disease, cirrhosis and hepatocellular carcinoma and the identification of the predictors of response to antiviral therapy is an important clinical issue.

AIM

To determine the independent contribution of factors including IL28B polymorphisms, IFN-gamma inducible protein-10 (IP-10) levels and the homeostasis model assessment of insulin resistance (HOMA-IR) score in predicting response to therapy in chronic hepatitis C (CHC).

METHODS

Multivariate analysis of factors predicting rapid (RVR) and sustained (SVR) virological response in 280 consecutive, treatment-naive CHC patients treated with peginterferon alpha and ribavirin in a prospective multicentre study.

RESULTS

Independent predictors of RVR were HCV RNA <400 000 IU/mL (OR 11.37; 95% CI 3.03-42.6), rs12980275 AA (OR 7.09; 1.97-25.56) and IP-10 (OR 0.04; 0.003-0.56) in HCV genotype 1 patients and lower baseline γ-glutamyl-transferase levels (OR=0.02; 0.0009-0.31) in HCV genotype 3 patients. Independent predictors of SVR were rs12980275 AA (OR 9.68; 3.44-27.18), age <40 years (OR=4.79; 1.50-15.34) and HCV RNA <400 000 IU/mL (OR 2.74; 1.03-7.27) in HCV genotype 1 patients and rs12980275 AA (OR=6.26; 1.98-19.74) and age <40 years (OR 5.37; 1.54-18.75) in the 88 HCV genotype 1 patients without a RVR. RVR was by itself predictive of SVR in HCV genotype 1 patients (OR 33.0; 4.06-268.32) and the only independent predictor of SVR in HCV genotype 2 (OR 9.0, 1.72-46.99) or genotype 3 patients (OR 7.8, 1.43-42.67).

CONCLUSIONS

In HCV genotype 1 patients, IL28B polymorphisms, HCV RNA load and IP-10 independently predict RVR. The combination of IL28B polymorphisms, HCV RNA level and age may yield more accurate pre-treatment prediction of SVR. HOMA-IR score is not associated with viral response.

[Techniques of preparation and indications of labile blood products]

Labile blood products are obtained from samples of whole blood or aphaeresis. The techniques of preparation evolve with technological advances, which allow both an increasing automation and an intensification of the sanitary safety of the blood products. Over the last ten years, thanks to the availability of new technologies, several measures have been introduced in order to reduce the risk of transmission of pathogens and prevent the onset of transfusion-related acute lung injury (TRALI): leukoreduction, use of platelet storage solutions, inactivation of plasma and presumably of platelets in a very near future. The control of transfusion risk also depends on proper use of labile blood products. To assist the prescriber in his treatment options and to standardize practices, the French Agency for Sanitary Safety of Health Products has issued recommendations in terms of utilization of blood products that are detailed in this review of major labile blood products available.

Impact of obesity, steatosis and insulin resistance on progression and response to therapy of hepatitis C

Clinical progression of chronic hepatitis C depends on several cofactors, which also have a negative affect on the rate of response to interferon-alpha-based therapy. Given the current worldwide prevalence of the metabolic syndrome, the impact of obesity and insulin resistance, and of their histopathological correlate, hepatic steatosis, on the natural history and management of chronic hepatitis C is undoubtedly very important. We will review some of the current knowledge on the clinical consequences of overweight/obesity, steatosis and insulin resistance on chronic hepatitis C, and discuss how this issue may be dealt with in clinical practice.

In situ high pressure and high temperature Raman studies of (1-x)SiO(2)xGeO(2) glasses

The structure of glasses in the binary system SiO(2)-GeO(2) has been studied by Raman spectroscopy. Our results are consistent with mixing of SiO(2) and GeO(2) tetrahedra. The changes induced by temperature and by pressure on the structure are monitored by in situ measurements on the same mixed glasses. Anomalous temperature dependences are observed not only for SiO(2) glass and GeO(2) glass but also for mixed glasses. Particular attention is focused on the pressure densification mechanism in mixed glasses. Via the pressure dependence of the width of the main Raman band, we show that the compression mechanism in mixed glasses is intermediate between that of the end members.

[Evaluation of left ventricular function: echocardiography, MRI or CT?]

The objective of this article is to clarify the advantages and limits of echocardiography, MRI, and CT for the determination of left ventricular (LV) function, emphasising the importance of evaluating global ventricular function. MRI is the reference technique, owing to its precision, reproducibility, and innocuous nature. However, echography is performed much more frequently because it is more widely available and easier to carry out. It is our reference technique in everyday practice. More recently, synchronised multi-slice tomodensitometry has provided dynamic reconstructed images of the left ventricle throughout the cardiac cycle, offering a succession of short axis views covering the entire volume of the ventricle. These acquisitions, in addition to non-invasive coronary angiography, allow the LV ejection fraction to be determined. With MRI, study of the LV function does not require any contrast medium to be injected and makes use of effective semi-automatic segmentation programs.

[Dynamics of interdisciplinary around a health care network: simultaneous programme design and evaluation planning]

This article reports on the evaluation experience of a multiple sclerosis care network in the Midi-Pyrénées region (MIPSEP). It shows how an evaluation team composed of public health doctors and sociologists progressively and naturally evolved from having a purely external observation role towards having a collaborative role actively working with the network's members and partners. A qualitative method was chosen for the data collection through interviews with the network's actors, and the frameworks for reference were constituted from official texts which defined the networks and their missions. Coming from a curative and healing culture, the network's actors were concerned primarily about how to organise themselves in order to better respond to the needs expressed by the patients. The various professional backgrounds and cultures, faced with different perspectives from innovation and confronted with the related difficulties, participated in a collective expertise exercise and collaborated in the construction process. This example supports an open, qualitative, evolutionary evaluation approach which is done in close proximity to the field and work on the ground. The study is timely given the current explosion of debate on evaluation methods. With a great deal of exchange and reflection on suitable tools and indicators as well as the respective roles of researchers, care givers and decision-makers, the results of this study advocate to favour multidisciplinary approaches, including opening up this process to funders and planning authorities rather than over-theorising about it, which only serves to enclose and paralyse a process that, on the contrary, should aim to be more inclusive. This could be a useful way to decompartmentalise and break down existing barriers within the health system.

Normal thyroid structure and function in rhophilin 2-deficient mice

Rhophilin 2 is a Rho GTPase binding protein initially isolated by differential screening of a chronically thyrotropin (TSH)-stimulated dog thyroid cDNA library. In thyroid cell culture, expression of rhophilin 2 mRNA and protein is enhanced following TSH stimulation of the cyclic AMP (cAMP) transduction cascade. Yeast two-hybrid screening and coimmunoprecipitation have revealed that the GTP-bound form of RhoB and components of the cytoskeleton are protein partners of rhophilin 2. These results led us to suggest that rhophilin 2 could play an important role downstream of RhoB in the control of endocytosis during the thyroid secretory process which follows stimulation of the TSH/cAMP pathway. To validate this hypothesis, we generated rhophilin 2-deficient mice and analyzed their thyroid structure and function. Mice lacking rhophilin 2 develop normally, have normal life spans, and are fertile. They have no visible goiter and no obvious clinical signs of hyper- or hypothyroidism. The morphology of thyroid cells and follicles in these mice were normal, as were the different biological tests performed to investigate thyroid function. Our results indicate that rhophilin 2 does not play an essential role in thyroid physiology.

The role of cyclic AMP and its effect on protein kinase A in the mitogenic action of thyrotropin on the thyroid cell

Cyclic AMP has been shown to inhibit cell proliferation in many cell types and to activate it in some. The latter has been recognized only lately, thanks in large part to studies on the regulation of thyroid cell proliferation in dog thyroid cells. The steps that led to this conclusion are outlined. Thyrotropin activates cyclic accumulation in thyroid cells of all the studied species and also phospholipase C in human cells. It activates directly cell proliferation in rat cell lines, dog, and human thyroid cells but not in bovine or pig cells. The action of cyclic AMP is responsible for the proliferative effect of TSH. It accounts for several human diseases: congenital hyperthyroidism, autonomous adenomas, and Graves' disease; and, by default, for hypothyroidism by TSH receptor defect. Cyclic AMP proliferative action requires the activation of protein kinase A, but this effect is not sufficient to explain it. Cyclic AMP action also requires the permissive effect of IGF-1 or insulin through their receptors, mostly as a consequence of PI3 kinase activation. The mechanism of these effects at the level of cyclin and cyclin-dependent protein kinases involves an induction of cyclin D3 by IGF-1 and the cyclic AMP-elicited generation and activation of the cyclin D3-CDK4 complex.

Angiotensin II stimulates alpha-skeletal actin expression in cadiomyocytes in vitro and in vivo in the absence of hypertension

Using a specific alpha-skeletal actin antibody, we have previously shown, that during hypertension-associated cardiac hypertrophy in the rat, the expression of alpha-skeletal actin in the myocardium is increased, but maintains focal distribution, compared to normotensive animals. In the present study, we have investigated whether alpha-skeletal actin expression can be induced in the absence of hypertension. For this purpose, we have examined transgenic mice overexpressing angiotensinogen exclusively in the heart. These animals are characterized by high cardiac angiotensin II levels and cardiac hypertrophy accompanied or not by high blood pressure depending on their genetic background, i.e. presence of one or two renin genes. Alpha-skeletal actin levels were highly increased in transgenic compared to wild-type myocardium independently of the number of renin genes, indicating that angiotensin II can stimulate alpha-skeletal actin expression in normotensive animals. Additional in vitro experiments using cultured mouse and rat cardiomyocytes showed that angiotension II not only increases alpha-skeletal actin expression but also induces an increase of its incorporation within II-bands compared to control cardiomyocytes. Angiotensin II increases also the expression of alpha-smooth muscle actin in sarcomeres of cardiomyocytes as well as in fibroblastic cells present within the culture.

Low TSH requirement and goiter in transgenic mice overexpressing IGF-I and IGF-Ir receptor in the thyroid gland

Through the cAMP signaling pathway, TSH stimulates thyroid follicular cell proliferation, differentiation, and function. Although the autocrine production of IGF-I in the thyroid gland suggests an important physiological function for this factor in these processes, the exact role of the IGF-I/IGF-I receptor system in vivo remains unclear. Although the mitogenic action of TSH requires the presence of IGF-I or insulin in primary culture of dog and human thyroid cells, IGF-I has an effect equal to and independent of the effect of TSH on cell proliferation in rat thyroid cell lines and may even be the main growth regulator in this case. To investigate the in vivo function of the IGF-I/IGF-I receptor system, transgenic mice overexpressing human IGF-I, IGF-I receptor, or both in the thyroid were generated. Adult transgenic mice did not present external signs of thyroid dysfunction, but mice overexpressing both transgenes had significantly increased gland weight and follicular lumen area. A decreased TSH level together with a slightly increased serum T(4) concentration and increased thyroidal iodine uptake were also observed, suggesting that IGF-I and IGF-I receptor stimulate thyroid function to some extent in vivo.

The lipid phosphatase SHIP2 controls insulin sensitivity

Insulin is the primary hormone involved in glucose homeostasis, and impairment of insulin action and/or secretion has a critical role in the pathogenesis of diabetes mellitus. Type-II SH2-domain-containing inositol 5-phosphatase, or 'SHIP2', is a member of the inositol polyphosphate 5-phosphatase family. In vitro studies have shown that SHIP2, in response to stimulation by numerous growth factors and insulin, is closely linked to signalling events mediated by both phosphoinositide-3-OH kinase and Ras/mitogen-activated protein kinase. Here we report the generation of mice lacking the SHIP2 gene. Loss of SHIP2 leads to increased sensitivity to insulin, which is characterized by severe neonatal hypoglycaemia, deregulated expression of the genes involved in gluconeogenesis, and perinatal death. Adult mice that are heterozygous for the SHIP2 mutation have increased glucose tolerance and insulin sensitivity associated with an increased recruitment of the GLUT4 glucose transporter and increased glycogen synthesis in skeletal muscles. Our results show that SHIP2 is a potent negative regulator of insulin signalling and insulin sensitivity in vivo.

The mouse SHIP2 (Inppl1) gene: complementary DNA, genomic structure, promoter analysis, and gene expression in the embryo and adult mouse

SHIP2 is a new member of the inositol polyphosphate 5-phosphatase family showing homology to SHIP1. The structure of both enzymes is characterized by the presence of a 5' SH2 domain, a central catalytic domain, and a 3' proline-rich region. Recent results suggest that SHIP2 and SHIP1 act downstream of various receptors by removing a phosphate from the 5' position of the phosphatidylinositol 3'-kinase phosphatidylinositol 3,4, 5-triphosphate product and of inositol 1,3,4,5-tetrakisphosphate. Human SHIP2 is highly expressed in adult heart, skeletal muscle, and placenta, whereas SHIP1 expression is limited to the hematopoietic system. We report here the molecular analysis of the mouse SHIP2 cDNA and the corresponding protein, the structure of the gene, and the identification of its promoter. SHIP2 mRNA expression was analyzed in embryonic and adult mouse tissues by reverse transcription-polymerase chain reaction and in situ hybridization. In embryonic day 15.5 mice, SHIP2 was strongly expressed in the liver, specific regions of the central nervous system, the thymus, the lung, and the cartilage perichondrium. In adult mice, SHIP2 mRNA was markedly present in the brain and the thymus and at different stages of spermatozoa maturation in the seminiferous tubules. The subtle differences in the protein structure of SHIP2 and SHIP1 as well as their different patterns of expression are discussed.

A subpopulation of cardiomyocytes expressing alpha-skeletal actin is identified by a specific polyclonal antibody

The NH(2)-terminal decapeptide of alpha-skeletal actin that contains a primary sequence specific for this isoform was used to raise a polyclonal antibody in rabbits. Using sequential affinity chromatography, we recovered from serum antibodies reacting exclusively with alpha-skeletal actin when tested by immunoblotting and immunofluorescence. Epitope mapping by means of competition assays with synthetic peptides indicated that the acetyl group and the first 9 amino acids are essential for specificity. The monospecific antibody was then used to investigate the distribution of alpha-skeletal actin in the myocardium of newborn and normal or hypertensive (with or without fibrotic areas) adult rats. Immunostaining of normal heart revealed that alpha-skeletal actin is diffusely distributed within practically all myocardial fibers of the newborn rat, whereas it is restricted to a small proportion of adult rat cardiomyocytes, which appear intensely stained. A correlation, albeit not complete, was found between the distribution of alpha-skeletal actin and beta-myosin heavy chain. During cardiac hypertrophy induced by aortic ligature between the renal arteries, the expressions of alpha-skeletal actin mRNA and protein were increased. The distribution of immunostaining had a focal pattern similar to that of normal adult rats, reactive fibers being more numerous and more intensely stained compared with normal myocardium. Positive fibers were particularly abundant at the periphery of fibrotic areas. Using this antibody, we have demonstrated for the first time the differential distribution of alpha-skeletal actin in heart tissues. Changes in the distribution of this isoform in hypertrophic heart provide new insight into the mechanisms by which the heart adapts to work overload. This antibody will prove useful in exploring the mechanisms of expression of alpha-skeletal actin and in defining its role in physiological and pathological situations.

Memory for pitch versus memory for loudness

The decays of pitch traces and loudness traces in short-term auditory memory were compared in forced-choice discrimination experiments. The two stimuli presented on each trial were separated by a variable delay (D); they consisted of pure tones, series of resolved harmonics, or series of unresolved harmonics mixed with lowpass noise. A roving procedure was employed in order to minimize the influence of context coding. During an initial phase of each experiment, frequency and intensity discrimination thresholds [P(C) = 0.80] were measured with an adaptive staircase method while D was fixed at 0.5 s. The corresponding physical differences (in cents or dB) were then constantly presented at four values of D: 0.5, 2, 5, and 10 s. In the case of intensity discrimination, performance (d') markedly decreased when D increased from 0.5 to 2 s, but was not further reduced when D was longer. In the case of frequency discrimination, the decline of performance as a function of D was significantly less abrupt. This divergence suggests that pitch and loudness are processed in separate modules of auditory memory.

Vitamin E mediated response of smooth muscle cell to oxidant stress

Oxidant stress is associated with diminution of antioxidant molecules, such as alpha-tocopherol. Alpha-tocopherol specifically decreases, in a concentration dependent way, the proliferation of vascular smooth muscle cells. At the same concentrations (10-50 microM) it induces inhibition of protein kinase C (PKC) activity. The latter event is not due to a decrease in PKC level or to alpha-tocopherol binding to PKC, but it results from increase of protein phosphatase 2A1 activity. In vitro data, as well as at a cellular level, demonstrates that protein phosphatase 2A1 is activated, in its trimeric structure--but not as a dimer by alpha-tocopherol. This activation is followed by PKC-alpha dephosphorylation. The activation of protein phosphatase 2A1 and deactivation of PKC-alpha affect the AP1 transcription factor, resulting in a change in the composition and the binding of this factor to DNA. By transfecting smooth muscle cell with a construct containing three TRE (TPA responsive elements), the promoter thymidine kinase and the reporter gene chloramphenicol-acetyl-transferase a modulation of gene expression by alpha-tocopherol is observed. Beta-tocopherol does not cause any of the responses observed with alpha-tocopherol and R,R,R-alpha-tocopherol is twice as potent as all-rac-alpha-tocopherol. When added together, beta-tocopherol prevents the effects of alpha-tocopherol indicating that the mechanism involved is not related to the radical-scavenging properties of these two molecules, which are essentially equal. By differential display analysis it has been found that several genes of smooth muscle cells are differentially transcribed in the presence of alpha-tocopherol but not beta-tocopherol. In particular, the gene of alpha-tropomyosin shows a transient enhancement of transcription as a function of the cell cycle time. Alpha-tropomyosin translation is also increased by alpha-tocopherol and not by beta-tocopherol. Because no changes of mRNA stability can be observed in the presence of alpha-tocopherol, the data supports the conclusion of a transcriptional control exerted by alpha-tocopherol on alpha-tropomyosin. Generally, the data strongly suggests the existence of a ligand/receptor type of mechanism at the basis of alpha-tocopherol action. It is concluded that an oxidative stress-induced diminution of alpha-tocopherol in smooth muscle cell activates a reaction cascade leading to changes in gene expression and increase in cell proliferation by a non-antioxidant mechanism.

alpha-Tocopherol specifically inactivates cellular protein kinase C alpha by changing its phosphorylation state

The mechanism of protein kinase C (PKC) regulation by alpha-tocopherol has been investigated in smooth-muscle cells. Treatment of rat aortic A7r5 smooth-muscle cells with alpha-tocopherol resulted in a time- and dose-dependent inhibition of PKC. The inhibition was not related to a direct interaction of alpha-tocopherol with the enzyme nor with a diminution of its expression. Western analysis demonstrated the presence of PKCalpha, beta, delta, epsilon, zeta and micro isoforms in these cells. Autophosphorylation and kinase activities of the different isoforms have shown that only PKCalpha was inhibited by alpha-tocopherol. The inhibitory effects were not mimicked by beta-tocopherol, an analogue of alpha-tocopherol with similar antioxidant properties. The inhibition of PKCalpha by alpha-tocopherol has been found to be associated with its dephosphorylation. Moreover the finding of an activation of protein phosphatase type 2A in vitro by alpha-tocopherol suggests that this enzyme might be responsible for the observed dephosphorylation and subsequent deactivation of PKCalpha. It is therefore proposed that PKCalpha inhibition by alpha-tocopherol is linked to the activation of a protein phosphatase, which in turn dephosphorylates PKCalpha and inhibits its activity.

The intermediate filament protein, vimentin, in the lens is a target for cross-linking by transglutaminase

Mere addition of Ca2+ to a lens cortical homogenate (bovine) generates a series of products composed of a variety of high molecular weight vimentin species. The Ca2+-induced cross-linking of this cytoskeletal element seems to be mediated by the intrinsic transglutaminase of lens, because the reaction could be blocked at the monomeric state of vimentin by the inclusion of small synthetic substrates of the enzyme dansylcadaverine or dansyl-epsilon-aminocaproyl-Gln-Gln-Ile-Val. These compounds are known to compete against the Gln or Lys functionalities of proteins that would participate in forming the Nepsilon(gamma-glutamyl)lysine protein-to-protein cross-links. The cytosolic transglutaminase-catalyzed reactions could be reproduced with purified bovine lens vimentin and also with recombinant human vimentin preparations. Employing the latter system, we have titrated the transglutaminase-reactive sites of vimentin and, by sequencing the dansyl-tracer-labeled segments of the protein, we have shown that residues Gln453 and Gln460 served as acceptor functionalities and Lys97, Lys104, Lys294, and Lys439 as electron donor functionalities in vimentin. The transglutaminase-dependent reaction of this intermediate filament protein might influence the shape and plasticity of the fiber cells, and the enzyme-catalyzed cross-linking of vimentin, in conjunction with other lens constituents, may contribute to the process of cataract formation.

Molecular basis of alpha-tocopherol control of smooth muscle cell proliferation

Rat and human vascular smooth muscle cell proliferation is specifically sensitive to alpha-tocopherol, but not beta-tocopherol. The former, but not the latter, is capable of limiting proliferation and inhibiting protein kinase C activity in a dose-dependent manner. The phenomenon occurs at concentrations in the range 10-50 microM. beta-tocopherol addition together with alpha-tocopherol, prevents both cell growth and protein kinase C inhibition. alpha-tocopherol increases de novo synthesis of protein kinase C molecules. The enzyme specific activity, however, is diminished, due to a decreased phosphorylation of protein kinase C, occurring in the presence of alpha-tocopherol. Experiments with protein kinase C isoform-specific inhibitors and precipitating antibodies show that the only isoform affected by alpha-tocopherol is protein kinase C-alpha. The effect of alpha-tocopherol is prevented by okadaic acid indicating a phosphatase of the PP2A type as responsible for protein kinase C-alpha dephosphorylation produced in the presence of alpha-tocopherol. At a gene level alpha-tocopherol but not beta-tocopherol induces a transient activation of alpha-tropomyosin gene transcription and protein expression. It is proposed that, by inhibiting protein kinase C activity via an activation of a phosphatase PP2A, alpha-tocopherol controls smooth muscle cell proliferation through changes in gene expression.

Signalling functions of alpha-tocopherol in smooth muscle cells

alpha-Tocopherol but not beta-tocopherol, activates protein phosphatase 2A, decreases protein kinase C activity and attenuates smooth muscle cell proliferation at physiological concentrations. beta-Tocopherol prevents the effects of alpha-tocopherol. Inhibition of protein kinase C alpha, but not of the other isoforms, by the inhibitor Gö6976 prevents the effect of alpha-tocopherol. Protein kinase C alpha, immunoprecipitated from alpha-tocopherol treated cells, is less phosphorylated and inactive. It is proposed that the specific activation of protein phosphatase 2A by alpha-tocopherol results in dephosphorylation and inactivation of protein kinase C alpha. Finally, this cascade of events leads to smooth muscle cell proliferation inhibition.

The perception of frequency peaks and troughs in wide frequency modulations. IV. Effects of modulation waveform

This work extends previous studies on the perceptual asymmetry between the local maxima and minima of wide frequency modulations (FMs) [L. Demany and K. I. McAnally, J. Acoust. Soc. Am. 96, 706-715 (1994); L. Demany and S. Clément, J. Acoust. Soc. Am. 97, 2454-2459 (1995); L. Demany and S. Clément, J. Acoust. Soc. Am. 98, 2515-2523 (1995)]. In experiment 1, subjects had to discriminate frequency shifts in the temporally central vertex of V- and A-shaped FMs imposed on 200-ms sinusoidal tone bursts. The precise shapes of these FMs varied in eight steps from quasi-triangles (with a durationless central vertex) to quasi-squares (with a long-duration central vertex). The central vertex was either a minimum or a maximum, but in each case the corresponding frequency was near 1000 Hz and the FM span was about 0.5 oct. For each FM shape, the discrimination threshold was lower when the vertex was a maximum than when it was a minimum, but (in four subjects out of five) this difference decreased monotonically as the FM became less and less triangular. FM shape had a remarkably small effect on the discrimination of the maxima, and the thresholds measured for the sharpest maxima were unexpectedly low. In subsequent experiments, subjects had to discriminate frequency shifts in the starting point or the final point of unidirectional FMs (tone glides) that spanned about 0.5 oct in 100 ms. The relevant frequency extremum was near 1000 Hz in each condition. At the final point of the glides, discrimination was better for rising glides than for falling glides. At the starting point of the glides, discrimination was better for falling glides than for rising glides. Thus discrimination was always better when the relevant frequency extremum was a maximum than when it was a minimum, and this effect was produced both "forward" and "backward." The latter fact suggests that the perceptual asymmetry of FM originates at least partly from central factors.

Alpha-tocopherol as a modulator of smooth muscle cell proliferation

The effects of alpha-tocopherol and beta-tocopherol have been studied in rat and human aortic smooth muscle cells. Alpha-tocopherol, but not beta-tocopherol, inhibited smooth muscle cell proliferation and protein kinase C in a dose-dependent manner, at concentrations ranging from 10 to 50 microM. Beta-tocopherol added simultaneously with alpha-tocopherol prevented both proliferation and protein kinase C inhibition. Protein kinase C inhibition was cell cycle-dependent and it was prevented by okadaic acid, a protein phosphatase inhibitor. Protein kinase C activity measured from aortas of cholesterol-fed rabbits was also inhibited by alpha-tocopherol. By using protein kinase C (PKC) isoform-specific inhibitors and immunoprecipitation reactions it was found that PKC-alpha was selectively inhibited by alpha-tocopherol. Further, an activation of protein phosphatase 2A by alpha-tocopherol was found, which caused PKC-alpha dephosphorylation and inhibition. Ultimately, this cascade of events at the level of cell signal transduction leads to the inhibition of smooth muscle cell proliferation.

Expression of P, S, and F1C adhesins by cytotoxic necrotizing factor 1-producing Escherichia coli from septicemic and diarrheic pigs

Nineteen papC-positive cytotoxic necrotizing factor 1 (CNF1)-producing Escherichia coli isolates from pigs with septicemia or diarrhea were tested for the presence of pap-, sfa-, and afa-related sequences encoding P/Prs, S/F1C, and Dr/AFA adhesins respectively. Production of adhesins by isolates was tested by mannose-resistant hemagglutination (MRHA), sialidase treatment of erythrocytes and particle agglutination tests. Production of P, S, and F1C fimbriae by isolates was also examined by immunofluorescence. All isolates were pap+ by PCR. Eighteen isolates (95%) were MRHA for ovine and human A erythrocytes and exhibited GalNac-GalNac receptor specificity associated with class III P(Prs) adhesins. Fifteen (79%) of the 19 isolates reacted with antisera specific for one or more different P fimbrial serotypes on immunofluorescence. Three of these isolates also demonstrated Gal-Gal receptor specificity associated with class I or II P fimbrial adhesins. Fifteen (79%) of the isolates were sfa+ by PCR. Seven of these isolates exhibited sialidase-sensitive MRHA of bovine and human O erythrocytes and reacted with serum specific for S fimbriae on immunofluorescence. Seven of the 8 sfa+ isolates which were MRHA-negative for bovine erythrocytes reacted with serum specific for F1C fimbriae on immunofluorescence. All isolates produced type 1 fimbriae as determined by mannose-sensitive agglutination of yeast cells. None of the isolates were afa+ by PCR or colony hybridization. Results suggest that most pap+ porcine CNF1-producing E. coli isolates express P fimbriae bearing class III (Prs) type adhesins. In addition, most of these isolates also produce S or F1C fimbriae.

The effect of alpha-tocopherol on the synthesis, phosphorylation and activity of protein kinase C in smooth muscle cells after phorbol 12-myristate 13-acetate down-regulation

Previous work had established that, in smooth muscle cells, alpha-tocopherol negatively regulates protein kinase C by preventing its activation [Tasinato, A., Boscoboinik, D., Bartoli, G. M., Maroni, P. & Azzi, A. (1995) Proc. Natl Acad. Sci. USA 92, 12190-12194]. In this study, the mechanism by which this event takes place has been analyzed. The regulation by alpha-tocopherol of protein kinase C expression, activity and phosphorylation has been followed during the synthesis of protein kinase C after its down-regulation by phorbol 12-myristate 13-acetate. The data show that protein kinase C isoenzyme alpha is synthesised significantly more (30% 72 h after down-regulation) in the presence of alpha-tocopherol. However, its activity is significantly less (45% diminution) and its phosphorylation state is also decreased (60% diminution). The effect of alpha-tocopherol appears not to be shared by the analogue beta-tocopherol, provided with similar radical-scavenging properties. The data are interpreted in terms of a diminution of protein kinase C phosphorylation, specifically caused by alpha-tocopherol, resulting in a decreased enzyme specific activity.

Loss of calcyphosine gene expression in mouse and other rodents

Calcyphosine-for calcium binding and regulated by cyclic AMP through phosphorylation protein-is a target of both the cyclic AMP and the Ca(+2)-phophatidylinositol cascades first isolated from dog thyroid, and then from rabbit and human brain. Although the exact function of this 24kD protein is unknown, calcyphosine could be implicated in the cross-signaling between these cascades to coordinate cellular proliferation and differentiation. Here, we report the sequence of a pseudogene which is the murine calcyphosine homologue, and demonstrate that it represents the unique sequence homologous to the dog calcyphosine gene in the murine genome. The lack of expression of this murine pseudogene in brain and thyroid-two major sites of dog calcyphosine expression-was extended to 5 other rodents, and suggest the existence of alternative pathway(s) to fill the function of calcyphosine in rodents.

Molecular requirements for polyamines binding to the antispermine monoclonal antibody Spm8-2

The monoclonal antispermine antibody Spm8-2 was obtained by immunizing mice with a thyroglobulin-spermine conjugate. The molecular requirements for polyamines binding to this antibody were investigated by ELISA binding and inhibition tests, using a variety of natural polyamines and synthetic polyamine analogs. Four major structural determinants are important for the binding of polyamines by the antibody: (1) terminal amino groups: N-alkylation of both terminal amino groups of the polyamines leads to an important drop in the affinity for the antibody; (2) number of methylene groups spacing the amino groups: the four carbon chains appear to present the optimum length since the antibody binds polyamines with repeats of the aminobutyl moiety more actively than their homologues with shorter or longer carbon chains; (3) number of amino groups: the affinity of Spm8-2 for free homologous polyamines varied in the following order: pentamines > tetramines > triamines > diamines, showing the importance of the number of positive charges of the polyamines in the antibody-antigen reaction; the importance of charges is further emphasized by the dependence of antibody binding on the ionic strength of the medium; (4) N-acylation of one terminal amino group: the antibody binds more actively N1-acetylspermidine than spermidine or spermine. The binding properties of Spm8-2 suggest the presence of two recognition sequences, one selective for N-acylaminopropyl moieties, the second for the aminobutyl moiety.

Analytical findings in a suicide involving sodium azide

A 47-year-old laboratory assistant ingested approximately 9 g of sodium azide powder and died 4 h later at a hospital. A high-performance liquid chromatographic method using diode-array detection has been developed for the determination of an azide benzoyl derivative in blood (after a simple deproteinization) and in several tissues (after homogenization in a neutral buffer and deproteinization of the supernatant). The blood concentration in this case was lower than those previously published. The highest azide concentration was found in lung tissue. A complete toxicological screening revealed the presence of cyanide in blood, which has been previously reported twice, but for the first time, it was confirmed by mass spectrometry. Whether the production of cyanide in the presence of azide took place in vivo or postmortem remains unknown; the nature of the metabolic pathway involved also remains unknown.

Spermine uptake is necessary to induce haemoglobin synthesis in murine erythroleukaemia cells

To determine whether intracellular uptake of spermine is necessary to induce haemoglobin synthesis in murine erythroleukaemia (MEL) DS 19 cells, we used single-step selection for resistance to N1,N12-bis(ethyl)spermine (BESM), a cytotoxic spermine analogue, to isolate clones deficient in polyamine transport. The cells were approximately 500-fold more resistant to BESM than parental cells and were unable to accumulate BESM, putrescine, spermidine or spermine. Addition of spermine to the polyamine-transport-deficient cells failed to induce haemoglobin synthesis. Hexamethylene-1,6-bisacetamide, a well-known differentiating agent, induced haemoglobin synthesis in both parental and resistant cells. Polyamine-transport-deficient cells transfected with DNA purified from the parental cell line were further selected for their ability to grow in the presence of alpha-difluoromethylornithine and putrescine. The transfectants had an active transport system for polyamines, and spermine added to their culture medium accumulated inside the cells and induced haemoglobin production. These findings indicate that intracellular spermine uptake is required to induce haemoglobin production in MEL cells.

The perception of frequency peaks and troughs in wide frequency modulations. III. Complex carriers

In widely frequency-modulated (FM) sine tones, local frequency maxima are perceived more accurately than local frequency minima [L. Demany and K. I. McAnally, J. Acoust. Soc. Am. 96, 706-715 (1994); L. Demany and S. Clément, J. Acoust. Soc. Am. 97, 2454-2459 (1995)]. The aim of the present work was to determine if a similar perceptual asymmetry exists for nonsinusoidal FM carriers. Within each stimulus, the logarithm of instantaneous frequency followed one cycle of a (2.5- or 5-Hz) cosine function, starting at phase pi in the "peak" condition and phase 0 in the "trough" condition. In each condition, subjects had to detect shifts in the frequency apex occurring at the temporal center of the stimuli. In experiment 1, the FM functions were imposed on complex tones consisting of a series of consecutive harmonics. Some of the stimuli were bandpass filtered in a 1-oct window with fixed edges. The measured thresholds were about four times lower in the peak condition than in the trough condition, which suggests that the asymmetry previously observed for "spectral" pitches also exists for "virtual" pitches. In experiment 2, the FM carriers were Shepard tones. With such carriers, the standard peak and trough stimuli could be made identical at both the apex and the end points. In spite of these local identities, the results were similar to those of experiment 1, which suggests that the perceptual asymmetry is not determined by local differences between the stimuli and is instead a genuine "motion" effect.(ABSTRACT TRUNCATED AT 250 WORDS)

The structure of polyamine analogues determines haemoglobin production and cytotoxicity in murine erythroleukaemia cells

The naturally occurring polyamine spermine induces haemoglobin synthesis in murine erythroleukaemia (MEL) cells. We have studied the ability of various polyamine analogues to inhibit cell growth and induce haemoglobin production. Polyamine analogues with free terminal amino groups were good inducers of haemoglobin production in MEL cells. Haemoglobin levels correlated with the number of positive charges: pentamines (five positive charges) were stronger inducers than tetramines (four positive charges). Compounds ethylated at their terminal amines were poor inducers of haemoglobin production but good inhibitors of MEL cell growth. These results provide evidence that polyamine analogues support specific biological functions of polyamines in MEL cells and suggest relationships between polyamine structure and function.

Spermine induces haemoglobin synthesis in murine erythroleukaemia cells

The naturally occurring polyamine spermine induces haemoglobin synthesis in murine erythroleukaemia (MEL) cells. Haemoglobin production was accompanied by accumulation of cytoplasmic beta-globin mRNA and growth inhibition, but not by cell-cycle block or changes in cell volume. Hexamethylene-bisacetamide (HMBA), a well known differentiating agent, also induces haemoglobin production, but causes a G1 block and decreases cell volume. These findings indicate that HMBA and spermine affect MEL cells differently, even though both induce haemoglobin production.

The perception of frequency peaks and troughs in wide frequency modulations. II. Effects of frequency register, stimulus uncertainty, and intensity

In widely frequency modulated sine tones, frequency maxima are perceived more accurately than frequency minima: A shift in a local frequency extremum is better detected when the extremum is a maximum than when it is a minimum, even within the same spectral region [L. Demany and K. I. McAnally, J. Acoust. Soc. Am. 96, 706-715 (1994)]. It is reported here that this perceptual asymmetry is about equally strong for frequency extrema near 250 and 1000 Hz, but weaker near 4000 Hz. It was also found that near 1000 Hz, the asymmetry is about equally strong for stimuli with an SPL of 35 and 70 dB, although the neural excitation patterns of a 1000-Hz tone probably have a different shape--and more specifically a different asymmetry--at these two levels. Finally, stimulus uncertainty was found to reduce the perceptual asymmetry: A weaker asymmetry was measured when the standard frequency extremum varied randomly from trial to trial than when it was fixed. The latter result, and the fact that the asymmetry did not decrease with training in the discrimination task, suggest that the asymmetry cannot be counteracted by "top-down" attentional processes and may be a preattentional phenomenon.