Seven years of gamma-ray spectrometry interlaboratory comparisons in Switzerland.

Since the 1990s, regular comparisons of gamma-ray spectrometry in Switzerland were organized to improve laboratory abilities to measure the radioactivity in the environment and food stuffs at typical routine levels. The activity concentration of the test samples and the evaluation of the associated uncertainties remained each year the main required test result. Over the years, the comparisons used certified reference solutions as well as environmental samples. The aim of this study is to research the effect of the comparisons on measurement quality. An analysis of the seven last interlaboratory comparisons revealed that the Swiss measurement capability is up to date. In addition, the results showed that the participants now have an improved evaluation of the uncertainties associated with their measurement.

Targetting of the ventro-intermediate nucleus using ultra-high field (7T) MRI for gamma knife surgery purposes: A pilot in vivo study on healthy subjects.

INTRODUCTION: Gamma Knife surgery (GKS) is a non-invasive neurosurgical stereotactic procedure, increasingly used as an alternative to open functional procedures. This includes targeting of the ventro-intermediate nucleus of the thalamus (e.g. Vim) for tremor. We currently perform an indirect targeting, as the Vim is not visible on current 3Tesla MRI acquisitions. Our objective was to enhance anatomic imaging (aiming at refining the precision of anatomic target selection by direct visualisation) in patients treated for tremor with Vim GKS, by using high field 7T MRI. MATERIALS AND METHODSH: Five young healthy subjects were scanned on 3 (T1-w and diffusion tensor imaging) and 7T (high-resolution susceptibility weighted images (SWI)) MRI in Lausanne. All images were further integrated for the first time into the Gamma Plan Software(®) (Elekta Instruments, AB, Sweden) and co-registered (with T1 was a reference). A simulation of targeting of the Vim was done using various methods on the 3T images. Furthermore, a correlation with the position of the found target with the 7T SWI was performed. The atlas of Morel et al. (Zurich, CH) was used to confirm the findings on a detailed analysis inside/outside the Gamma Plan. RESULTS: The use of SWI provided us with a superior resolution and an improved image contrast within the basal ganglia. This allowed visualization and direct delineation of some subgroups of thalamic nuclei in vivo, including the Vim. The position of the target, as assessed on 3T, perfectly matched with the supposed one of the Vim on the SWI. Furthermore, a 3-dimensional model of the Vim-target area was created on the basis of the obtained images. CONCLUSION: This is the first report of the integration of SWI high field MRI into the LGP, aiming at the improvement of targeting validation of the Vim in tremor. The anatomical correlation between the direct visualization on 7T and the current targeting methods on 3T (e.g. quadrilatere of Guyot, histological atlases) seems to show a very good anatomical matching. Further studies are needed to validate this technique, both by improving the accuracy of the targeting of the Vim (potentially also other thalamic nuclei) and to perform clinical assessment.

Glycogen synthase 2 is a novel target gene of peroxisome proliferator-activated receptors.

Glycogen synthase 2 (Gys-2) is the ratelimiting enzyme in the storage of glycogen in liver and adipose tissue, yet little is known about regulation of Gys-2 transcription. The peroxisome proliferator-activated receptors (PPARs) are transcription factors involved in the regulation of lipid and glucose metabolism and might be hypothesized to govern glycogen synthesis as well. Here, we show that Gys-2 is a direct target gene of PPARalpha, PPARbeta/delta and PPARgamma. Expression of Gys-2 is significantly reduced in adipose tissue of PPARalpha-/-, PPARbeta/delta-/- and PPARgamma+/- mice. Furthermore, synthetic PPARbeta/delta, and gamma agonists markedly up-regulate Gys-2 mRNA and protein expression in mouse 3T3-L1 adipocytes. In liver, PPARalpha deletion leads to decreased glycogen levels in the refed state, which is paralleled by decreased expression of Gys-2 in fasted and refed state. Two putative PPAR response elements (PPREs) were identified in the mouse Gys-2 gene: one in the upstream promoter (DR-1prom) and one in intron 1 (DR-1int). It is shown that DR-1int is the response element for PPARs, while DR-1prom is the response element for Hepatic Nuclear Factor 4 alpha (HNF4alpha). In adipose tissue, which does not express HNF4alpha, DR-1prom is occupied by PPARbeta/delta and PPARgamma, yet binding does not translate into transcriptional activation of Gys-2. Overall, we conclude that mouse Gys-2 is a novel PPAR target gene and that transactivation by PPARs and HNF4alpha is mediated by two distinct response elements.

The optimal dividend barrier in the Gamma-Omega model

In the traditional actuarial risk model, if the surplus is negative, the company is ruined and has to go out of business. In this paper we distinguish between ruin (negative surplus) and bankruptcy (going out of business), where the probability of bankruptcy is a function of the level of negative surplus. The idea for this notion of bankruptcy comes from the observation that in some industries, companies can continue doing business even though they are technically ruined. Assuming that dividends can only be paid with a certain probability at each point of time, we derive closed-form formulas for the expected discounted dividends until bankruptcy under a barrier strategy. Subsequently, the optimal barrier is determined, and several explicit identities for the optimal value are found. The surplus process of the company is modeled by a Wiener process (Brownian motion).

TLR3 and Rig-like receptor on myeloid dendritic cells and Rig-like receptor on human NK cells are both mandatory for production of IFN-gamma in response to double-stranded RNA.

Cross-talk between NK cells and dendritic cells (DCs) is critical for the potent therapeutic response to dsRNA, but the receptors involved remained controversial. We show in this paper that two dsRNAs, polyadenylic-polyuridylic acid and polyinosinic-polycytidylic acid [poly(I:C)], similarly engaged human TLR3, whereas only poly(I:C) triggered human RIG-I and MDA5. Both dsRNA enhanced NK cell activation within PBMCs but only poly(I:C) induced IFN-gamma. Although myeloid DCs (mDCs) were required for NK cell activation, induction of cytolytic potential and IFN-gamma production did not require contact with mDCs but was dependent on type I IFN and IL-12, respectively. Poly(I:C) but not polyadenylic-polyuridylic acid synergized with mDC-derived IL-12 for IFN-gamma production by acting directly on NK cells. Finally, the requirement of both TLR3 and Rig-like receptor (RLR) on mDCs and RLRs but not TLR3 on NK cells for IFN-gamma production was demonstrated using TLR3- and Cardif-deficient mice and human RIG-I-specific activator. Thus, we report the requirement of cotriggering TLR3 and RLR on mDCs and RLRs on NK cells for a pathogen product to induce potent innate cell activation.

PPARβ/δ ameliorates fructose-induced insulin resistance in adipocytes by preventing Nrf2 activation

We studied whether PPARβ/δ deficiency modifies the effects of high fructose intake (30% fructose in drinking water) on glucose tolerance and adipose tissue dysfunction, focusing on the CD36-dependent pathway that enhances adipose tissue inflammation and impairs insulin signaling. Fructose intake for 8weeks significantly increased body and liver weight, and hepatic triglyceride accumulation in PPARβ/δ-deficient mice but not in wild-type mice. Feeding PPARβ/δ-deficient mice with fructose exacerbated glucose intolerance and led to macrophage infiltration, inflammation, enhanced mRNA and protein levels of CD36, and activation of the JNK pathway in white adipose tissue compared to those of water-fed PPARβ/δ-deficient mice. Cultured adipocytes exposed to fructose also exhibited increased CD36 protein levels and this increase was prevented by the PPARβ/δ activator GW501516. Interestingly, the levels of the nuclear factor E2-related factor 2 (Nrf2), a transcription factor reported to up-regulate Cd36 expression and to impair insulin signaling, were increased in fructose-exposed adipocytes whereas co-incubation with GW501516 abolished this increase. In agreement with Nrf2 playing a role in the fructose-induced CD36 protein level increases, the Nrf2 inhibitor trigonelline prevented the increase and the reduction in insulin-stimulated AKT phosphorylation caused by fructose in adipocytes. Protein levels of the well-known Nrf2 target gene NAD(P)H: quinone oxidoreductase 1 (Nqo1) were increased in water-fed PPARβ/δ-null mice, suggesting that PPARβ/δ deficiency increases Nrf2 activity; and this increase was exacerbated in fructose-fed PPARβ/δ-deficient mice. These findings indicate that the combination of high fructose intake and PPARβ/δ deficiency increases CD36 protein levels via Nrf2, a process that promotes chronic inflammation and insulin resistance in adipose tissue.

Clinical and biochemical responses after Gamma Knife surgery for a dopamine-secreting paraganglioma: case report.

The efficacy of Gamma Knife surgery (GKS) in local tumor control of non-secreting paragangliomas (PGLs) has been fully described by previous studies. However, with regard to secreting PGL, only one previous case report exists advocating its efficacy at a biological level. The aims of this study were: 1) to evaluate the safety/efficacy of GKS in a dopamine-secreting PGL; 2) to investigate whether the biological concentrations of free methoxytyramine could be used as a marker of treatment efficacy during the follow-up. We describe the case of a 62-year-old man diagnosed with left PGL. He initially underwent complete surgical excision. Thirty months after, he developed recurrent biological and neuroradiological disease; the most sensitive biomarker for monitoring the disease, concentration of plasma free methoxytyramine, started to increase. GKS was performed at a maximal marginal dose of 16 Gy. During the following 30 months, concentration of free methoxytyramine gradually decreased from 0.14 nmol/l (2*URL) before GKS to 0.09 nmol/l, 6 months after GKS and 0.07 nmol/l at the last follow-up after GKS (1.1*URL), confirming the efficacy of the treatment. Additionally, at 30 months there was approximately 36.6% shrinkage from the initial target volume. The GKS treatment was safe and effective, this being confirmed clinically, neuroradiologically and biologically. The case illustrates the importance of laboratory tests taking into account methoxytyramine when analyzing biological samples to assess the biochemical activity of a PGL. In addition, the identification of methoxytyramine as a unique positive biomarker could designate it for the monitoring of tumor relapse after treatments, including Gamma Knife surgery.

Charting developmental EEG gamma changes in the auditory modality /

The oscillation of neuronal circuits reflected in the EEG gamma frequency may be fundamental to the perceptual process referred to as binding (the integration of various thoughts and perceptions into a coherent picture). The aim of our study was to expand our knowledge of the developmental course ofEEG gamma in the auditory modality. 2 We investigated EEG 40 Hz gamma band responses (35.2 to 43.0 Hz) using an auditory novelty oddball paradigm alone and with a visual-number-series distracter task in 208 participants as a function of age (7 years to adult) at 9 sites across the sagital and lateral axes (F3, Fz, F4, C3, Cz, C4, P3, Pz, P4). Gamma responses were operationally defined as change in power or a change in phase synchrony level from baseline within two time windows. The evoked gamma response was defined as a significant change from baseline occurring between 0 to 150 ms after stimulus onset; the induced gamma response was measured from 250 to 750 ms after stimulus onset. A significant evoked gamma band response was found when measuring changes in both power and phase synchrony. The increase in both measures was maximal at frontal regions. Decreases in both measures were found when participants were distracted by a secondary task. For neither measure were developmental effects noted. However, evoked gamma power was significantly enhanced with the presentation of a novel stimulus, especially at the right frontal site (F4); frontal evoked gamma phase synchrony also showed enhancement for novel stimuli but only for our two oldest age groups (16-18 year olds and adults). Induced gamma band responses also varied with task-dependent cognitive stimulus properties. In the induced gamma power response in all age groups, target stimuli generated the highest power values at the parietal region, while the novel stimuli were always below baseline. Target stimuli increased induced synchrony in all regions for all participants, but the novel stimulus selectively affected participants dependent on their age and gender. Adult participants, for example, exhibited a reduction in gamma power, but an increase in synchrony to the novel stimulus within the same region. Induced gamma synchrony was more sensitive to the gender of the participant than was induced gamma power. While induced gamma power produced little effects of age, gamma synchrony did have age effects. These results confirm that the perceptual process which regulates gamma power is distinct from that which governs the synchronization for neuronal firing, and both gamma power and synchrony are important factors to be considered for the "binding" hypothesis. However, there is surprisingly little effect of age on the absolute levels of or distribution of EEG gamma in the age range investigated.

Does Gamma-aminobutyric acid function as a plant resistance mechanism against phytophagous insect activity? /

Gamma-aminobutyric acid (GAB A) is a ubiquitous non-protein amino acid synthesized via the decarboxylation of L-glutamate in a reaction catalyzed by the cytosolic enzyme L-glutamate decarboxylase (GAD). In animals it functions as an inhibitory neurotransmitter. In plants it accumulates rapidly in response to various stresses, but its function remains unclear. The hypothesis that GABA accumulation in leaf tissue may function as a plant resistance mechanism against phytophagous insect activity was investigated. GABA accumulation in response to mechanical stimulation, mechanical damage and insect activity was demonstrated. In wt tobacco (Nicotiana tabacum cv Samsun), mechanical stimulation or damage caused GABA to accumulate within 2 min from mean levels of 14 to 37 and 1~9 nmol g-l fresh weight (FW), respectively. In the transgenic tobacco strain CaMVGAD27c overexpressing Petunia GAD, the same treatments caused GABA to accumulate from 12 to 59 and 279 nmol g-l FW, respectively. In the transgenic tobacco strain CaMVGADilC 11 overexpressing Petunia GAD lacking an autoinhibitory domain, mechanical stimulation or damage caused GABA to accumulate from 180 to 309 and 630 nmol g-l FW, respectively. Ambulatory activity by tobacco budworm (TBW) larvae (Heliothis virescens) on leaves of CaMVGAD27c tobacco caused GABA to accumulate from 28 to 80 nmol g-l FW within 5 min. Ambulatory and leaf-rolling activity by oblique banded leaf roller (OBLR) larvae (Choristoneura rosaceana cv Harris) on wt soybean leaves (Glycine max cv Harovinton) caused GABA to accumulate from 60 to 1123 nmol g-l FW within 20 min. Increased GABA levels in leaf tissue were shown to affect phytophagous preference in TBW larvae presented with wt and transgenic tobacco leaves. When presented with leaves of Samsun wt and CaMVGAD27c plants, TBW larvae consumed more wt leaf tissue (640 ± 501 S.D. mm2 ) than transgenic leaf tissue (278 ± 338 S.D. mm2 ) nine times out of ten. When presented with leaves of Samsun wt and CaMVGAD~C11 plants, TBW larvae consumed more transgenic leaf tissue (1219 ± 1009 S.D. mm2 ) than wt leaf tissue (28 ± 31 S.D. mm2 ) ten times out of ten. These results indicate that: (1) ambulatory activity of insect larvae on leaves results in increased GABA levels, (2) transgenic tobacco leaves with increased capacity for GABA synthesis deter feeding, and (3) transgenic tobacco leaves with constitutively higher GABA levels stimulate feeding.

Changes in the magnitude and pattern of translocation of photoassimilated ¹CO in soybean plants following an acute exposure to gamma radiation /

Young soybean plants (Glycine ~. L. cultivar Harosoy '63), grown under controlled conditions, were exposed to gamma radiation on a single occasion. One hour following exposure to 3,750 rads, the mature trifoliate leaf of the soybean plant was isolated in a closed system and permitted to photoassimilate approximately 1-5 pCi of 14C02 for 15 minutes. After an additional 45 minute-period, the plant was sacrificed and the magnitude of translocation and distribution pattern of 14C determined. In the non-irradiated plants 18~ of the total 14C recovered was outside the fed leaf blades and of this translocated 14c, 28~ was above the node of the fed leaf, 38~ in the stem below the node, 28~ in the roots and 7~ in the petiole. As well, in the irradiated plants, a smaller per cent (6~) of the total 14 C recovered was exported out of the source leaf blades. Of this translocated 14c , a smaller per cent (20~) was found in the apical region above the node of the source leaf and a higher per cent (45~) was recovered from the stem below the node and in the petiole (11~). The per cent of exported 14 C recovered from the root was unaffected by the radiation. Replacement of the shoot apex with 20 ppm IAA immediately following irradiation, only J partially increased the magnitude of translocation but did completely restore the pattern of distribution to that observed in the non-irradiated plants. From supplementary studies showing a radiationinduced reduction of photosynthetic rates in the source leaf and a reduction of the cumulative stem and leaf lengths in the apical sink region, the observed effects of radiation on the translocation process have been correlated to damage incurred by the source and sink regions. These data suggest that the reduction in the magnitude of translocation is the result of damage to both the source and sink regions rather than the phloem conducting tissue itself, whereas the change in the pattern of translocation is probably the result of a reduced rate of 14C-assimilate movement caused by a radiation-induced decrease of sink metabolism, especially the decrease in the metabolism of the apical sink.

Rapid [Gamma]-amino acid synthesis and the inhibition of the growth and development of oblique banded leaf-roller larvae

The hypothesis that rapid y-aminobutyric acid (GABA) accumulation is a plant defense against phytophagous insects was investigated. Simulation of mechanical damage resulting from phytophagous insect activity increased soybean (Glycine max L.) leaf GABA 10- to 25-fold within 1 to 4 min. Pulverizing leaf tissue resulted in a value of 2. 15 (±O. 11 SE) ~mol GABA per gram fresh weight. Increasing the GABA levels in a synthetic diet from 1.6 to 2.6 Jlffiol GABA per gram fresh weight reduced the growth rates, developmental rates, total biomass (50% reduction), and survival rates (30% reduction) of cultured Oblique banded leaf-roller (OBLR) (Choristonellra rosacealla Harris) larvae. In field experiments OBLR larvae were found predominantly on young terminal leaves which have a reduced capacity to produce GABA in response to mechanical damage. Glutamate decarboxylase (GAD) is a cytosolic enzyme which catalyses the decarboxylation of L-Glu to GABA. GAD is a calmodulin binding enzyme whose activity is stimulated dramatically by increased cytosolic H+ or Ca2 + ion concentrations. Phytophagous insect activity will disrupt the cellular compartmentation of H+ and Ca2 +, activate GAD and subsequent GABA accumulation. In animals GABA is a major inhibitory neurotransmitter. The possible mechanisms resulting in GABA inhibited growth and development of insects are discussed.

Efecto comparado de la radiación gamma sobre fibroblastos humanos diploides derivados del cultivo de pulmón y de adenocarcinoma mamario

Tesis (Maestría en Ciencias con Especialidad en Patología) UANL

Endurecimiento superficial del acero por difusión del carbono en hierro gamma

Tesis (Maestro en Ciencias de la Ingeniería Mecánica, con especialidad en Metalurgia) UANL Facultad de Ingeniería Mecánica y Eléctrica , 1994