Handling interferences in 89Sr and 9°Sr measurements of reactor coolant water: a method based on strontium separation chemistry.

Measurements for determining the activity of (89)Sr and (90)Sr in reactor coolant water are associated with limitations due to interferences from radionuclides with similar chemical properties and ß(-)-energies. From a measurement bias point-of-view these interferences would result mainly in an overestimated activity concentration of (90)Sr. In order to address the interference problem, a common and well-known method was used in order to show the need for sufficient decontamination. An improvement was achieved by taking the sample through two initial strontium separations in order to increase the decontamination factor. This method determines the activity concentration of (89)Sr and (90)Sr, via its daughter nuclide (90)Y, by Cherenkov counting. This work is primarily based on theoretical calculations of strontium-, yttrium- and other potential interfering radionuclide ratios after instant fission. The work done to confirm the theoretical calculations were carried through on spiked strontium standard solutions and fresh reactor coolant water. The reactor coolant water was known to contain interferences at a composition resembling that of instant fission. The detection limit for double separation was calculated to 0.17 Bq/kg for (90)Sr and 0.38 Bq/kg for (89)Sr. When using methods that solely rely on strontium resins, this paper shows that the decontamination factor (DF) is significantly higher when using double separation than that of a single separation. The paper also shows that the DF of an initial double strontium separation is as effective when it comes to removing high ratio interferences as separations done with both Sr- and Ln-resin (EiChrom Technologies, Inc., 2003; Tovedal et al., 2009b). However, 'old' samples, where e.g. (140)Ba and (89)Sr has decayed, does not benefit from double separation. Furthermore, samples with low ratios of interfering radionuclides does not benefit from using this method either, seeing as this is a more time consuming method due to the double separations.

Cytokine mRNA expression in bronchoalveolar lavage cells during Dictyocaulus viviparus infection in calves.

The purpose of this study was to monitor local cytokine responses to Dictyocaulus viviparus in calves during primary infection and re-infection. Bronchoalveolar lavage fluid (BALF) was collected weekly from experimentally infected calves and interleukin-2 (IL-2), IL-4, IL-5, IL-10 and IFN-γ mRNA expression was quantified in BALF cells. The major finding was a prominent transient increase in IL-4 mRNA expression, compared with that of uninfected calves, observed in BALF cells collected 2-3 weeks post-primary D. viviparus infection. At 2 weeks post-infection, macroscopic worms were also first observed in BALF. Calves re-infected after 10 weeks were partially immune which was evident at slaughter 5 weeks post-infection as a lower worm burden than in previously naïve calves infected at the same time. IL-4 mRNA expression in BALF cells 2 weeks post-re-infection was increased compared with that of uninfected animals but not as high as that of primarily infected calves. BALF cell expression of the other cytokines tested for was not as clearly effected by the D. viviparus infection. It seems likely that the strong IL-4 response observed during primary infection reflects an innate response to the worms that may initiate an ensuing Th2 response, which confers protective immunity.

Circulatory arrest in late pregnancy: caesarean section a vital decision for both mother and child.

Circulatory arrest during pregnancy is extremely rare and there should be a well-planned strategy for its management in all hospitals. To consider the priority of the mother's life over the child's and an unwarranted pre-term delivery may lead to hesitancy and uncertainty and jeopardize both of them. In these situations, speed is a priority. Cardiopulmonary resuscitation should commence immediately. The anaesthesiologist should be well aware of the possible advantage of a caesarean section. Even if the obstetrician is responsible for the decision to perform the operation, the anaesthesiologist should strongly support the action. An 'emergency caesarean kit' with the essential surgical instruments should be immediately available in every labour ward and emergency department.

Ultrashort single-shot pulse characterization with high spatial resolution using localized nonlinearities in ferroelectric domain walls.

Second-order nonlinearities localized in the regions adjacent to the ferroelectric domain wall in KTiOPO(4) are used to realize a single-shot noncollinear frequency-resolved optical gating arrangement for ultrashort pulse characterization with high spatial resolution. Cerenkov phase matching is utilized to achieve spectral dispersion and makes the same nonlinear crystal applicable over wide spectral ranges from the visible to the mid-infrared.

Efficient doubling of femtosecond pulses in aperiodically and periodically poled KTP crystals.

Efficient doubling of femtosecond pulses in periodically and aperiodically poled KTP crystals is demonstrated by employing the quasiphasematched frequency conversion technique. Conversion efficiencies as high as 60% were achieved using either aperiodically or periodically poled KTP nonlinear crystals in an extracavity, single-pass configuration using a diode-pumped femtosecond Yb:KYW laser as the pump source. The temporal characteristics of the frequency-doubled pulses as a function of focusing conditions in a "thick" nonlinear crystal regime have been investigated experimentally and pulses as short as 177 fs have been generated at around 520 nm under strong focusing conditions using a KTP crystal with aperiodic poling.

Active and passive hybrid mode-locking of a Nd:YVO(4) laser with a single partially poled KTP crystal.

We report on a Nd:YVO(4) laser mode-locked with a hybrid active and passive modulator consisting of a single partially poled KTP crystal. The periodically poled part provides negative cascaded Kerr-lensing, which together with intracavity soft and hard apertures gives passive modulation. Active phase modulation comes from the electro-optic effect by applying a voltage over the unpoled part of the crystal. The active modulation provides pulse lengths of about 95 ps, which initiate pulse shortening and self-sustained passive mode-locking by the cascaded Kerr effect. The repetition rate of the laser was 94 MHz and the output power was 350 mW, with a bandwidth of 0.235 nm and pulse lengths down to 6.9 ps.

Generation of 2.8 ps pulses by mode-locking a Nd:GdVO4 laser with defocusing cascaded Kerr lensing in periodically poled KTP.

A Nd:GdVO4 laser mode locked by self-defocusing cascaded Kerr lens in PPKTP is presented. A strong pulse shortening mechanism is produced by the interplay of group velocity mismatch and the cavity design. The cavity had a repetition rate of 200 MHz and the mode-locked output power was 350 mW. Pulses as short as 2.8 ps were obtained with a bandwidth of 0.6 nm.

Simultaneous search for multiple QTL using the global optimization algorithm DIRECT.

MOTIVATION: A simultaneous search is necessary for maximizing the power to detect epistatic quantitative trait loci (QTL). The computational complexity demands that the traditional exhaustive search be replaced by a more efficient global optimization algorithm. RESULTS: We have the previously known algorithm adapted DIRECT, to the problem of simultaneous mapping of multiple QTL. We have compared DIRECT with standard exhaustive search and a genetic algorithm previously used for QTL mapping in two dimensions. In all two- and three-QTL test cases, DIRECT accurately finds the global optimum two to four orders of magnitude faster than when using an exhaustive search, and one order of magnitude faster than when using the genetic algorithm. Thus, randomization testing for determining empirical significance thresholds for at least three QTL is made feasible by the use of DIRECT. AVAILABILITY: The code of the prototype implementation is available at http://user.it.uu.se/~kl/qtl_software.html

Neurotrophin receptors and enteric neuronal development during metamorphosis in the amphibian Xenopus laevis.

During metamorphosis, the frog intestine goes through a dramatic shortening with extensive apoptosis and regeneration in the epithelial layer and connective tissue. Our aim was to study changes in the enteric nervous system represented by one inhibitory (vasoactive intestinal polypeptide; VIP) and one excitatory (substance P, neurokinin A; SP/NKA) nerve population and concomitant changes in neurotrophin receptor occurrence during this development in the gut of Xenopus laevis adults and tadpoles at different stages of metamorphosis (NF stages 57-66). Sections were incubated with antibodies against the neurotrophin Trk receptors and p75NTR, and the neurotransmitters VIP and SP/NKA. Trk-immunoreactive nerves increased dramatically but transiently in number during early metamorphic climax. Nerves immunoreactive for p75NTR were present throughout the gut, decreased in number in the middle intestine during climax, and increased in the large intestine during late metamorphosis. The percentage of VIP-immunoreactive nerves did not change during metamorphosis. SP/NKA-immunoreactive nerves were first apparent at NF stages 61-62 in the middle intestine and increased in the stomach and large intestine during metamorphosis. Endocrine cells expressing SP/NKA increased in number in stomach, proximal, and middle intestine during metamorphic climax. Thus, neurotrophin receptors are expressed transiently in neurons of the enteric nervous system during metamorphosis in Xenopus laevis and SP/NKA innervation is more abundant in the intestine of the postmetamorphic frog than in the tadpole.

Simultaneous second-harmonic generation with two orthogonal polarization states in periodically poled KTP.

Simultaneous generation of second-harmonic light with orthogonal polarizations in the blue spectral region is demonstrated by use of typeII and typeI quasi-phase matching for the nonlinear coefficients d(33) , d(24) , and d(32) in periodically poled KTP. The second-harmonic power ratio in both polarization states can be tuned by the fundamental polarization and (or) the periodically poled KTP temperature. Femtosecond pulse frequency-doubling efficiencies of as much as 39.5% W (-1) and 8.1% W (-1) are demonstrated in 7-mm periodically poled KTP for typeI and typeII processes, respectively. The efficiency limitations caused by various effects of the group-velocity mismatch are discussed.

Evolution of vertebrate neuropeptides.

This review describes some of the most typical features in the evolution of neuropeptides. Neuropeptides are synthesized like other polypeptides and proteins, with an amino acid sequence determined by the DNA sequence of the corresponding gene. Mutations of bases in the coding regions of the DNA lead to changes in amino acid sequence, and explain the differences in amino acid sequence of a certain neuropeptide in different animal species. The more distantly related two species are, the more substitutions can be found in one and the same neuropeptide. The biologically active part of the neuropeptide is usually the most conserved part. Neuropeptides also form families of closely related peptides, where several members may occur in one animal species. This is due to gene or exon duplications followed by mutations. Gene splicing and posttranslational processing decides the gene product in a single cell. Difference in sequence may cause difference in function, but more often than not, members of a family appear to produce the same effect. Three neuropeptide families, the tachykinins, the neuropeptide Y family, and the vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating peptide family will be described in more detail.

Occurrence of neurotrophin receptors and transmitters in the developing Xenopus gut.

The ontogeny of gut innervation in the anuran amphibian Xenopus laevis was studied using immunohistochemistry on sections of whole larvae from NF stages 38-52. Immunoreactivity to acetylated tubulin confirmed the presence of nerve fibres as early as stages 38-39. Actin immunoreactivity was found at stage 41, indicating the presence of smooth muscle cells. Trk-like neurotrophin receptors were occasionally found in nerve fibres as soon as stages 38-39. Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) immunoreactivities coexisted in nerves innervating the gut wall from stages 40-41, and nitric oxide synthase (NOS) from stage 42. Substance P/neurokinin A (SP/NKA) occurred at stage 42. In all these cases, the first fibres were observed in the oesophagus. Calcitonin gene-related peptide (CGRP) was first observed in nerves at stage 48. In general, VIP/PACAP and NOS innervation was denser than the tachykinin innervation. In conclusion, the development of nerve fibres in the Xenopus gut is probably dependent on neurotrophins that may act via Trk-like receptors and occur before the gut wall is fully organised morphologically. Feeding in Xenopus larvae starts at NF stage 45. The study demonstrates that several of the transmitters investigated are expressed in the gut innervation (and in endocrine cells) prior to this stage.

Large veins in the Atlantic cod (Gadus morhua) and the rainbow trout (Oncorhynchus mykiss) are innervated by neuropeptide-containing nerves.

Previous studies have shown that fish veins are reactive to several hormones known to exist in the fish circulation. Besides this humoral control, another possible means of active regulation of venous return is by autonomic nervous control of venous tone. This study therefore investigated the presence of a perivascular innervation of major veins in the Atlantic cod (Gadus morhua) and the rainbow trout (Oncorhynchus mykiss) using immunohistochemical methods. Histological staining was employed to investigate the smooth muscle distribution in the vessel walls. Vasoactive intestinal polypeptide-immunoreactive nerve fibers were found to be widespread in the venous system of G. morhua and O. mykiss, while pituitary adenylate cyclase-activating polypeptide-immunoreactive fibers were demonstrated in the duct of Cuvier of both species. Fibers containing neurokinin A and/or substance P were found in the duct of Cuvier and the posterior cardinal vein of both species and in the hepatic portal vein of O. mykiss. Calcitonin-gene related peptide-immunoreactive fibers were present in the duct of Cuvier of both species and in the hepatic portal vein of O. mykiss. Galanin-immunoreactive fibers were found in the duct of Cuvier in O. mykiss and in the hepatic portal vein of both species. Co-existence of neuropeptides in the perivascular nerve fibers was investigated by double labelling. Vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating polypeptide-immunoreactive fibers were found in both species. Vasoactive intestinal polypeptide/galanin-immunoreactive fibers and vasoactive intestinal polypeptide/calcitoningene related peptide-immunoreactive fibers were found in G. morhua but not in O. mykiss. This study gives further evidence for an active venoregulation by autonomic nerves in teleost fish.

Gastrin-releasing peptides from Xenopus laevis: purification, characterization, and myotropic activity.

Two molecular forms of gastrin-releasing peptide (GRP) were isolated from an extract of the intestine of the tetraploid frog Xenopus laevis. The primary structure of GRP-1 (APTSQQHTEQ(10)LSRSNINTRG(20) SHWAVGHLM.NH(2)) differs from that of GRP-2 by a single amino acid substitution (Asn(15)--> Thr(15)). GRP-(20-29) peptide (neuromedin C) was also isolated from the extract. Synthetic GRP-1 produced concentration-dependent contractions of longitudinal smooth muscle strips from Xenopus cardiac stomach (pD(2) = 8.93 +/- 0.32; n = 6). The responses were unaffected by tetrodotoxin, atropine, and methysergide, indicating a direct action of the peptide on smooth muscle cells. GRP-1 elicited concentration-dependent relaxations of precontracted (5 microM carbachol) circular smooth muscle strips from the same region (pD(2) = 8.96 +/- 0.21; n = 8). The responses were significantly (P < 0.05) attenuated (71 +/- 24% decrease in maximum response; n = 6) by indomethacin, indicating mediation, at least in part, by prostanoids. Despite the fact that Xenopus GRP-1 differs from pig GRP at 15 amino acid sites, both peptides are equipotent and equally effective for both contractile and relaxant responses, demonstrating that selective evolutionary pressure has acted to conserve the functional COOH-terminal domain in the peptide. The data suggest a physiologically important role for GRP in the regulation of gastric motility in X. laevis.

Effects of trout endothelin on the motility of gastrointestinal smooth muscle from the trout and rat.

Trout endothelin (ET), previously isolated from the kidney of the rainbow trout Oncorhynchus mykiss, contains four amino acid substitutions at residues 4-7 compared with rat ET-1. Trout ET produced sustained and concentration-dependent contractions of strips of longitudinal smooth muscle from trout stomach (pD(2) = 7.52 +/- 0.06) and proximal small intestine (pD(2) = 7.80 +/- 0.10) and from rat fundus (pD(2) = 7.78 +/- 0.14). Rat ET-1 was equipotent with trout ET for contraction of rat fundus and 2- to 3-fold more potent for contraction of trout gastrointestinal tissues. In contrast, rat ET-1 was 10- to 20-fold more potent than trout ET in constricting isolated rings of vascular tissue from trout efferent branchial artery and cardinal vein and from rat aorta (Y. Wang et al., 1999, Am. J. Physiol. 277, R1605-R1611). It is known that the contractile effects of ET-1 on rat fundus are mediated through the ET(B) receptor and effects on the rat aorta are mediated through the ET(A) receptor. We propose, therefore, that trout gastrointestinal tissues express an ET(B)-type receptor that differentiates poorly between trout ET and rat ET-1, whereas trout vascular tissues express an ET(A)-type receptor that is preferentially activated by rat ET-1. The rat ET-1-induced contractions of the trout gastrointestinal tissues are in part indirect, involving a serotoninergic neuronal pathway in the intestine and a noncholinergic, nonserotoninergic pathway in the stomach.

Effects of cod bradykinin and its analogs on vascular and intestinal smooth muscle of the Atlantic cod, Gadus morhua.

The effects of [Arg(0),Trp(5),Leu(8)]-BK (cod [Arg(0)]BK) on vascular preparations from branches of the cod celiac artery and on longitudinal smooth muscle preparations from the cod intestine were investigated. Cod [Arg(0)]BK (3 x 10(-8) M) caused a relaxation of the celiac artery precontracted with adrenaline. The relaxation was abolished by the cyclooxygenase inhibitor indomethacin, suggesting that the effect is mediated through the release of prostaglandins, but there was no evidence for the involvement of leukotrienes or nitric oxide in the response. In the intestinal preparations, cod [Arg(0)]BK produced concentration-dependent contractions (pD(2) = 8.28 +/- 0.16). Experiments with N-terminally and C-terminally truncated analogs and with alanine-substituted analogs of cod [Arg(0)]BK demonstrate that the central amino acid Gly(4) and the C-terminal amino acids Leu(8) and Arg(9) are the most important in determining the conformation of the peptide that interacts with the receptor. The results indicate that the ligand binding properties of the cod BK receptor are considerably different from the receptor present in trout tissues and may resemble those of the mammalian B(2) receptor more closely.

Increased plasma hyaluronan in severe pre-eclampsia and eclampsia.

Pre-eclampsia is a serious multi-system disorder with general endothelial disease, often with a component of hepatic dysfunction. The pathogenesis of preeclampsia is not fully understood, and no specific diagnostic tests are available for early and reliable diagnosis, or for monitoring of the disease process. Hyaluronan is an extracellular matrix polysaccharide present at low concentrations in plasma. Normally, it is rapidly eliminated from the blood by the liver. Increased concentrations of circulating hyaluronan are seen in conditions with impaired hepatic function such as liver cirrhosis, and hyaluronan concentrations have previously been used to evaluate hepatic function in other diseases. In the present study, 11 pregnant women admitted to the intensive care unit with severe pre-eclampsia or eclampsia were studied. As control 31 healthy pregnant women, 18 undergoing vaginal delivery and 13 caesarean section, were included. Plasma hyaluronan was measured before and after delivery. Increased concentrations of plasma hyaluronan were found in the pre-eclampsia group both before (171 (75-586) microg/L (p<0.01)) and after delivery (215 (124-768) microg/L (p<0.001)) (median and inter-quartile range), as compared to both caesarean section (13 (7-28) microg/L before and 28 (18-48) microg/L after delivery) and vaginal delivery healthy controls (12 (8-24) microg/L before and 30 (13 63) microg/L after delivery). In the control groups, a small increase in plasma hyaluronan was seen after delivery, after both caesarean section (p<0.05) and vaginal delivery (p<0.01). In conclusion, plasma hyaluronan is increased in severe pre-eclampsia and eclampsia. The cause of the increase is unknown.

Nitric oxide, a potent vasodilator of the aortic anastomosis in the estuarine crocodile, Crocodylus porosus.

The effects of five neuropeptides (CGRP, SOM, SP, NPY, VIP), L-NAME (nitric oxide synthase inhibitor), and adrenaline on the contractile tone of the aortic anastomosis in the estuarine crocodile, Crocodylus porosus, were investigated. None of the neuropeptides, which had previously been found to be present in the aortic anastomosis, had any direct effect on the tension developed by ring preparations. L-NAME itself significantly increased the basal tone of the vascular ring preparations, suggesting a tonic release of nitric oxide in the preparation. Adrenaline produced concentration-dependent vasoconstrictions that were counteracted by profound reflex vasodilatations that were susceptible to blockade by L-NAME. Immunohistochemistry revealed the presence of nitric oxide synthase and tyrosine hydroxylase-containing (indicating the presence of a adrenergic innervation) nerve fibres in the adventitia and adventitio-medial border of the aortic anastomosis. These data demonstrate opposing actions of adrenaline and nitric oxide on the vascular smooth muscle in the anastomosis of the C. porosus. The morphology of the anastomosis, with the extremely thick muscular vessel wall, suggests a sphincter-like function for this vessel that could be controlled mainly by adrenergic and nitrergic mechanisms.

The control of gut motility.

Gut motility in non-mammalian vertebrates as in mammals is controlled by the presence of food, by autonomic nerves and by hormones. Feeding and the presence of food initiates contractions of the stomach wall and subsequently gastric emptying, peristalsis, migrating motor complexes and other patterns of motility follow. This overview will give examples of similarities and differences in control systems between species. Gastric receptive relaxation occurs in fish and is an enteric reflex. Cholecystokinin reduces the rate of gastric emptying in fish as in mammals. Inhibitory control of peristalsis is exerted, e.g. by VIP, PACAP, NO in fish and amphibians, while excitatory stimuli arise from nerves releasing tachykinins, acetylcholine or serotonin (5-HT). In crocodiles, we have found the presence of the same nerve types, although the effects on peristalsis have not been studied. Recent studies on signal transduction in the gut smooth muscle of fish and amphibians suggest that external Ca2+ is of great importance, but not the only source of Ca2+ recruitment in tachykinin-, acetylcholine- or serotonin-induced contractions of rainbow trout and Xenopus gastrointestinal smooth muscle. The effect of acetylcholine involves reduction of cAMP-levels in the smooth muscle cells. It is concluded that, in general, the control systems in non-mammalian vertebrates are amazingly similar between species and animal groups and in comparison with mammals.

Sulfur shuffle: modulating enzymatic activity by thiol-disulfide interchange.

The facile modulation of biological processes is an important goal of biological chemists. Here, a general strategy is presented for controlling the catalytic activity of an enzyme. This strategy is demonstrated with ribonuclease A (RNase A), which catalyzes the cleavage of RNA. The side-chain amino group of Lys41 donates a hydrogen bond to a nonbridging oxygen in the transition state for RNA cleavage. Replacing Lys41 with a cysteine residue is known to decrease the value of k(cat)/K(m) by 10(5)-fold. Forming a mixed disulfide between the side chain of Cys41 of K41C RNase A and cysteamine replaces the amino group and increases k(cat)/K(m) by 10(3)-fold. This enzyme, which contains a mixed disulfide, is readily deactivated by dithiothreitol. Forming a mixed disulfide between the side chain of Cys41 and mercaptopropyl phosphate, which is designed to place a phosphoryl group in the active site, decreases activity by an additional 25-fold. This enzyme, which also contains a mixed disulfide, is reactivated in the presence of dithiothreitol and inorganic phosphate (which displaces the pendant phosphoryl group from the active site). An analogous control mechanism could be installed into the active site of virtually any enzyme by replacing an essential residue with a cysteine and elaborating the side chain of that cysteine into appropriate mixed disulfides.