Estimation of foetal brain dose from I-131 in the foetal thyroid

The ingestion of I-131 by pregnant women can have consequences for the developing foetus, in particular brain function. As the foetal thyroid accumulates iodine from the twelfth week of gestation onwards, the determination of foetal brain dose resulting from such I-131 accumulation is essential. Normal dosimetric methods fail to treat the case of foetus. Using an approximation method based on the MIRD approach, a foetal dose estimation scheme is developed to allow the determination of foetal brain dose from foetal thyroid irradiation. Dose values are obtained for the foetus based on the maternal intake of I-131. It was found that the choice of biokinetic model for the mother/foetus has a large impact on the determined dose estimate.     

rab3 mediates cortical granule exocytosis in the sea urchin egg

Egg activation at fertilization in the sea urchin results in the exocytosis of approximately 15,000 cortical granules that are docked at the plasma membrane. Previously, we reported that several integral membrane proteins modeled in the SNARE hypothesis, synaptotagmin, VAMP, and syntaxin, in addition to a small GTPase of the ras superfamily, rab3, were present on cortical granules (Conner, S., Leaf, D., and Wessel, G., Mol. Reprod. Dev. 48, 1-13, 1997). Here we report that rab3 is associated with cortical granules throughout oogenesis, during cortical granule translocation, and while docked at the egg plasma membrane. Following cortical granule exocytosis, however, rab3 reassociates with a different population of vesicles, at least some of which are of endocytic origin. Because of its selective association with cortical granules in eggs and oocytes, we hypothesize that rab3 functions in cortical granule exocytosis. To test this hypothesis, we used a strategy of interfering with rab3 function by peptide competition with its effector domain, a conserved region within specific rab types. We first identified the effector domain sequence in Lytechinus variegatus eggs and find the sequence 94% identical to the effector domain of rab3 in Stronglocentrotus purpuratus. Then, with synthetic peptides to different regions of the rab3 protein, we find that cortical granule exocytosis is inhibited in eggs injected with effector domain peptides, but not with peptides from the hypervariable region or with a scrambled effector peptide. Additionally, effector-peptide-injected eggs injected with IP3 are blocked in their ability to exocytose cortical granules, suggesting that the inhibition is directly on the membrane fusion event and not the result of interference with the signal transduction mechanism leading to calcium release. We interpret these results to mean that rab3 functions in the regulation of cortical granule exocytosis following vesicle docking.     

Comment. Remarks on the LUC public key system

The authors of [Remarks on the LUC public key system, see ibid., vol. 30, p. 123, 1994] consider the Lucas function on which the public cryptosystem LUC proposed by Smith and Lennon [1993] is based. For a finite field G with m∈G, the Lucas function V_n(m) is defined by the second order linear recurrence relation V_n(m)=mV_n-1(m)-V_n-2(m) where V_o (m)=2, V₁(m)=m. The characteristic polynomial f of the Lucas function is f(x)=x²-mx+1, and V_x(m)=α ^x+α^-x where α is a root of f. We now consider some of the results of and give concise proofs     

Fluorescence in situ hybridization analysis of chromosome 1p36 deletions in human MYCN amplified neuroblastoma

Artificial illumination is an important factor in the management of layers. In this study, a new monochromatic light system was developed for egg layers. Prelaying pullets (Lohmann) were marked and housed in nine light and temperature control rooms (15 battery cages, 3 hens per cage; n = 45), divided into three light treatments: 0.1 and 0.01 W/m2 light intensity using light emitting diode (LED) lamps and 0.1 W/m2 using mini-fluorescent bulbs (PL) (control). In each of the LED rooms, three wavelengths were tested: 560 (n = 9), 660 (n = 9), 880 (n = 6), and 660 intermitted lighting (15 min light 45 min dark, 660IN) (n = 9). Birds were exposed to 12 h light and 12 h of darkness using PL lamps. At 21 wk of age, the light period was increased to 12.75 h by using 5.5 h of LED lamps and 7.25 of PL light source for Groups 1 and 2, the third group received 12.75 h of PL light. Until 28 wk of age, light hours increased by 0.5 h/w using LED light for Groups 1 and 2 and PL source for the third group, reaching 16 h of light at 28 wk of age. Egg production and feed consumption were recorded daily; egg components were recorded weekly for 10 mo. A significant reduction in egg production was observed in all 880nm groups; no differences in egg production and quality were found in the other groups. Feed consumption was significantly lower by 7% in all 0.01 W/m2 groups. We suggest that an important reduction in rearing costs of laying hens may be obtained by using this system.     

Effect of neurocatin on the activity of monoamine oxidase B in rat brain synaptosomes

When the phenotype of neurons in pre- and paravertebral sympathetic ganglia are compared, there are marked differences in NGF dependence, neuropeptide content, connectivity and electrophysiological properties. The trophic interactions that induce these differences are currently poorly understood. One explanation is that prevertebral neurons receive a second neurotrophic signal, other than NGF, from their target of innervation. If this is the case, neurons in the prevertebral ganglia should express another neurotrophin receptor, in addition to the NGF receptor (trkA). To test this prediction, the level of expression of three neurotrophin receptors, trkA, trkB and trkC, were examined in one paravertebral sympathetic ganglia, the SCG, and two prevertebral ganglia, the celiac and superior mesenteric ganglia. It was found that mRNA encoding the full-length form of the trkB receptor was barely expressed in the SCG. Significantly higher levels of full-length trkB mRNA expression were found in the prevertebral ganglia. Ligands of the trkB receptor may, therefore, contribute to the differentiation and/or survival of some prevertebral sympathetic neurons.     

Modal convection and its effect on the stability of EDM wires

Recently, it has been shown that EDM wires undergo thermal buckling at low axial transport speeds and a series of transport instabilities at high axial transport speeds. Hence, only intermediate speeds ensure the straight wire configuration, which is needed for high-accuracy cutting. These conclusions are based on the assumption that the convective heat transfer coefficient remains piecewise constant along the length of the wire. However, a recent study on convection from a vibrating, flexible body shows that the convection coefficient becomes modal. The present study re-examines the wire stability problem with this modal effect in mind. It is shown that at low axial transport speeds, the straight wire configuration may be stable. Its stability hinges on vibration—large amplitude motion implies increased convection and increased stability from thermal buckling. At high transport speeds, the system still undergoes the reported transport instabilities. This work shows that the well-defined intermediate speed range is not so well-defined in the presence of wire vibrations.     

Predicting postdischarge opiate abstinence from admission measures of motivation and confidence.

Admission scores from a model comprising 3 motivation factors concerning the cessation of heroin use and a confidence scale concerning postdischarge abstinence were tested for their ability to predict postdischarge outcomes in patients beginning inpatient opiate detoxification. Statistically significant prediction of abstinence from heroin 30 days after discharge and the number of heroin-free days in the 3 months following admission was based on the confidence scale and a factor concerned with externally imposed constraints on continued heroin use. The single-scale confidence measure made the largest contribution to each prediction, indicating that such scales may be potentially useful outcome predictors for postdischarge abstinence. External constraints on heroin use may not provide a basis for success in this treatment modality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)