Hybrid microwave oscillators with a virtual cathode

A review is given of the developments and theoretical investigations of a fundamentally new class of microwave devices, namely, hybrid microwave oscillators with a virtual cathode, which combine the useful properties of virtual cathodes with the advantages of those traditional microwave oscillators that operate with subcritical-current beams and have a high efficiency in generating ultrarelativistic electron beams. Among such devices are the following: a hybrid diffractional microwave oscillator with a virtual cathode, a hybrid gyrodevice with a virtual cathode, a hybrid beam-plasma vircator, a hybrid gyrocon with a virtual cathode, a hybrid Cherenkov oscillator with a virtual cathode, a hybrid microwave oscillator of the “vircator + traveling-wave tube” type, an original two-beam tube with a virtual cathode, and a klystron-like vircator.     

Do Bells Affect Behaviour and Heart Rate Variability in Grazing Dairy Cows?

In alpine regions cows are often equipped with bells. The present study investigated the impact of wearing a bell on behaviour and heart rate variability in dairy cows. Nineteen non-lactating Brown-Swiss cows with bell experience were assigned to three different treatments. For 3 days each, cows were equipped with no bell (control), with a bell with inactivated clapper (silent bell) or with a functional bell (functional bell). The bells weighed 5.5 kg and had frequencies between 532 Hz and 2.8 kHz and amplitudes between 90 and 113 dB at a distance of 20 cm. Data were collected on either the first and third or on all 3 days of each treatment. Whereas duration of rumination was reduced with a functional bell and a silent bell compared with no bell, feeding duration was reduced with a silent bell and was intermediate with a functional bell. Head movements were reduced when wearing a silent bell compared with no bell and tended to be reduced when wearing a functional compared to no bell. With a functional bell, lying duration was reduced by almost 4 hours on the third day of treatment compared with the first day with a functional bell and compared with no bell or a silent bell. All additional behavioural measures are consistent with the hypothesis of a restriction in the behaviour of the cows wearing bells, although this pattern did not reach significance. There was no treatment effect on heart rate variability, suggesting that the bells did not affect vago-sympathetic balance. An effect of experimental day was found for only 1 out of 10 behavioural parameters, as shown by a decrease in lying with a functional bell on day 3. The results indicate behavioural changes in the cows wearing a bell over 3 days, without indication of habituation to the bell. Altogether, the behavioural changes suggest that the behaviour of the cows was disturbed by wearing a bell. If long-lasting, these effects may have implications for animal welfare.     

Probabilistic reinforcement and neurotic breakdown in unrestrained dogs]

The substitution of a constant reinforcement for a random one with a probability of 0.5 in experiments on two dogs with a simple motor stereotype was attended with nervous breakdowns with motor excitation, inadequate orienting reactions or passive-defensive behaviour. The change in the probability of reinforcement from 0.5 to 0.3 had a positive effect in experiments on one dog, while in the other it developed drowsiness. In two other dogs with a complicated stereotype, the change in the mode of reinforcement was attended with a peculiar preventive effect of probabilistic, but ordered reinforcement in experimental surroundings, including signals with a probabilistic random reinforcement as well. In this case the dogs displayed primarily signs of emotional stress only. Behaviour was somewhat disturbed in one animal only when testing signals with a probabilistic random reinforcement.     

Inhibition of D-3-aminoisobutyrate-pyruvate aminotransferase by 5-fluorouracil and alpha-fluoro-beta-alanine.

Among pyrimidine derivatives, we found that 5-fluorouracil potently inhibited purified rat liver D-3-aminoisobutyrate-pyruvate aminotransferase, whereas 5-fluorouridine did so to a much lesser extent. 5-Fluorouracil acted as a competitive inhibitor against beta-alanine with a Ki of 56 microM, and was uncompetitive against pyruvic acid, with a Ki of 73 microM. alpha-Fluoro-beta-alanine, a metabolite of 5-fluorouracil, was also a competitive inhibitor with respect to beta-alanine with a Ki of 8.0 mM. 5-Fluorouracil acted also as a competitive inhibitor of 4-aminobutyrate aminotransferase with respect to beta-alanine with a Ki value of 1.9 mM, and was uncompetitive against 2-oxoglutaric acid, with a Ki of 1.8 mM.     

The lyotropic liquid crystal properties of n-octyl 1-O-beta-D-glucopyranoside and related n-alkyl pyranosides

X-ray diffraction patterns have been obtained for the lyotropic phases of n-octyl 1-O-beta-D-glucopyranoside and the related n-heptyl, n-nonyl and n-decyl compounds with water. The octyl compound exhibits all three liquid crystal phases and forms a micellar solution with increasing solvation, when the crystal come into contact with water at room temperature. The X-ray diffraction patterns show a one-dimensional lamellar phase with [dx] = 28.4 A, a three-dimensional face-centered cubic phase with [a] = 51.2 A, and a two-dimensional hexagonal phase with [a] = [b] = 36.7 A. The micellar solution has a distribution pattern with a maximum at [dx] = 33.8 A. Crystals of the heptyl, nonyl and decyl derivatives form only the lamellar phases and the micellar solution on contact with water at room temperature.     

Measles immunisation in children with allergy to egg.

OBJECTIVE--To examine the occurrence of adverse reactions to measles vaccine given as a single dose to children with egg allergy, and to determine if the administration of single dose to children with a positive result in an intradermal skin prick test with the vaccine is associated with adverse reactions. DESIGN--Review of results of immunisation and prospective study of 96 consecutively presenting children given intradermal skin testing with the vaccine. SETTING--Children''s allergy centre. SUBJECTS--410 children sensitive to egg referred to the allergy unit for advice about measles immunisation. MAIN OUTCOME MEASURES--Nature and severity of reactions associated with the administration of measles vaccine. RESULTS--All children had a positive result in a skin prick test with egg white, and five had a positive result in a skin prick test with vaccine. Of 96 consecutive children, 46 had a positive result in an intradermal test with vaccine. After immunisation with a full dose (0.5 ml) of vaccine adverse reactions were associated with a mild reaction in four children, none of whom required treatment. Only one of the 46 children with a positive result in an intradermal vaccine skin test had a reaction associated with vaccine administration. None of the children with a positive result in a skin prick test with measles vaccine reacted to the vaccine. The rate of minor reactions to the vaccine not requiring treatment was 0.98% (95% confidence interval 0.27% to 2.48%) and serious reactions requiring treatment was 0% (0% to 0.9%). CONCLUSION--Children with IgE mediated allergic reactions to egg protein should be investigated and managed by practitioners with special knowledge in this subject. Measles immunisation should be performed in a setting where any adverse reactions can be dealt with appropriately. Skin tests and measles vaccine and desensitisation are not necessary.     

Influence of prior and visual information on eye movements in amblyopic children

This study analyzed the characteristics of pursuit and assessed the influence of prior and visual information on eye velocity and saccades in amblyopic and control children, in comparison to adults. Eye movements of 41 children (21 amblyopes and 20 controls) were compared to eye movements of 55 adults (18 amblyopes and 37 controls). Participants were asked to pursue a target moving at a constant velocity. The target was either a ‘standard’ target, with a uniform color intensity, or a ‘noisy’ target, with blurry edges, to mimic the blurriness of an amblyopic eye. Analysis of pursuit patterns showed that the onset was delayed, and the gain was decreased in control children with a noisy target in comparison to amblyopic or control children with a standard target. Furthermore, a significant effect of prior and visual information on pursuit velocity and saccades was found across all participants. Moreover, the modulation of the effect of visual information on the pursuit velocity by group, that is amblyopes or controls with a standard target, and controls with a noisy target, was more limited in children. In other words, the effect of visual information was higher in control adults with a standard target compared to control children with the same target. However, in the case of a blurry target, either in control participants with a noisy target or in amblyopic participants with a standard target, the effect of visual information was larger in children.

     

Twin pregnancy with complete hydatidiform mole and coexisting fetus following ovulation induction with a non-prescribed clomiphene citrate regimen: a case report

Introduction

Until now, studies on paracetamol given intravenously have mainly been performed with the pro-drug propacetamol or with paracetamol in preterm babies above 32 weeks of gestation. Studies in these babies indicate that intravenous paracetamol is tolerated well, however studies on the efficacy of intravenous paracetamol are lacking. There are no pharmacokinetic data on the administration of multiple doses of paracetamol in preterm babies with a gestational age below 32 weeks.

Case presentation

We present a case series of nine Caucasian preterm babies, six boys and three girls, with a mean gestational age of 28.6 weeks (range 25.9 to 31.6 weeks). Case one, a girl with a gestational age of 25 weeks and six days, presented with necrotizing enterocolitis. In the second case, a female baby with a gestational age of 26 weeks and two days presented with hematoma. In case three, a female baby with a gestation of 26 weeks and one day developed intraventricular hemorrhage. In case four, a male baby with a gestational age of 31 weeks and four days presented with pain after vacuum delivery. Case five, a female baby born after a gestation of 29 weeks and six days presented with hematoma. In case six, a male baby with a gestation of 30 weeks and six days presented with hematoma. In case seven, a male baby, born with a gestational age of 30 weeks and six days, presented with caput succedaneum and hematoma. In case eight, a male baby, born after a gestation of 28 weeks and four days, developed abdominal distention. Case nine, a female baby, born with a gestational age of 27 weeks and three days presented with hematoma. These babies were treated with intravenous paracetamol 15 mg/kg every six hours. Serum concentrations and aspartate transaminase were determined after prolonged administration. Pain scores were assessed using the Premature Infant Pain Profile.

Conclusion

Paracetamol serum concentrations ranged from 8 to 64 mg/L after eight to 12 doses of intravenous paracetamol. Adequate analgesia was obtained in seven babies. During paracetamol therapy the median serum level of aspartate transaminase was 20 U/L (range 12 to 186 U/L). This case series indicates that prolonged intravenous administration of paracetamol in preterm babies with a gestational age of less than 32 weeks is tolerated well in the first days after birth. However, in the absence of proper pharmacokinetic data in this age group we cannot advocate the use of paracetamol intravenously.     

An integrated, stacked microlaboratory for biological agent detection with DNA and immunoassays

An integrated, stacked microlaboratory for performing automated electric-field-driven immunoassays and DNA hybridization assays was developed. The stacked microlaboratory was fabricated by orderly laminating several different functional layers (all 76 x 76 mm(2)) including a patterned polyimide layer with a flip-chip bonded CMOS chip, a pressure sensitive acrylic adhesive (PSA) layer with a fluidic cutout, an optically transparent polymethyl methacrylate (PMMA) film, a PSA layer with a via, a patterned polyimide layer with a flip-chip bonded silicon chip, a PSA layer with a fluidic cutout, and a glass cover plate layer. Versatility of the stacked microlaboratory was demonstrated by various automated assays. Escherichia coli bacteria and Alexa-labeled protein toxin staphylococcal enterotoxin B (SEB) were detected by electric-field-driven immunoassays on a single chip with a specific-to-nonspecific signal ratios of 4.2:1 and 3.0:1, respectively. Furthermore, by integrating the microlaboratory with a module for strand displacement amplification (SDA), the identification of the Shiga-like toxin gene (SLT1) from E. coli was accomplished within 2.5 h starting from a dielectrophoretic concentration of intact E. coli bacteria and finishing with an electric-field-driven DNA hybridization assay, detected by fluorescently labeled DNA reporter probes. The integrated microlaboratory can be potentially used in a wide range of applications including detection of bacteria and biowarfare agents, and genetic identification.     

Two-dimensional crystallization on lipid monolayers and three-dimensional structure of sticholysin II, a cytolysin from the sea anemone Stichodactyla helianthus

Sticholysin II (Stn II), a potent cytolytic protein isolated from the sea anemone Stichodactyla helianthus, has been crystallized on lipid monolayers. With Fourier-based methods, a three-dimensional (3D) model of Stn II, up to a resolution of 15 A, has been determined. The two-sided plane group is p22(1)2, with dimensions a = 98 A, b = 196 A. The 3D model of Stn II displays a Y-shaped structure, slightly flattened, with a small curvature along its longest dimension (51 A). This protein, with a molecular mass of 19. 2 kDa, is one of the smallest structures reconstructed with this methodology. Two-dimensional (2D) crystals of Stn II on phosphatidylcholine monolayers present a unit cell with two tetrameric motifs, with the monomers in two different orientations: one with its longest dimension lying on the crystal plane and the other with this same axis leaning at an angle of approximately 60 degrees with the crystal plane.     

Filter combinations and light sources for fluorescence microscopy of quinacrine mustard or quinacrine stained chromosomes

Summary The efficiency of various combinations of primary and secondary filters, and light sources for the fluorescence microscopy of chromosomes stained with quinacrine mustard or quinacrine has been studied quantitatively. Using epi-illumination, strong fluorescence could be obtained with a mercury or xenon lamp in combination with two KP 490 short-wave pass interference filters (tilted to an angle of 60° with the excitation beam) as primary filter, and a K 490 as a secondary filter. The combination of a mercury lamp and a narrow band interference filter with a maximal transmission at about 436 nm as a primary filter together with a K 490 secondary filter results in a good visual image contrast, sufficiently strong fluorescence, and a relatively slow rate of fading.     

New data on aberrant spermatozoa in the ejaculate of Sus domesticus

This paper describes 16 new types of aberrant spermatozoa observed by scanning electron microscopy in the ejaculate of two healthy, sexually mature Landrace boars. The new anomalies observed were 1) spermatozoa with folded tail and abnormal head; 2) tailless spermatozoa with an abnormal connecting piece; 3) immature spermatozoa with two tails of the same length, fused and coiled; 4) spermatozoa with two tails of the same length, fused and coiled, and a small, rounded head; 5) spermatozoa with two fused tails and a wide head; 6) spermatozoa with three tails of the same length, fused and coiled; 7) immature spermatozoa with two heads and two fused tails; 8) spermatozoa with two heads, one at each tip of the tail; 9) spermatozoa with a short, folded tail and a triangular head; 10) spermatozoa with a short tail lacking the intermediate piece; 11) spermatozoa with a short tail, without the main piece and with a long intermediate piece; 12) spermatozoa with a short tail, without the main piece and with a rough head; 13) spermatozoa with small, rounded head; 14) spermatozoa with small, aberrant heads; 15) spermatozoa with small, bacillary heads; and 16) immature spermatozoa with tapering heads.     

Fluorescence resonance energy transfer analysis of subunit stoichiometry of the epithelial Na+ channel

Activity of the epithelial Na(+) channel (ENaC) is rate-limiting for Na(+) (re)absorption across electrically tight epithelia. ENaC is a heteromeric channel comprised of three subunits, alpha, beta, and gamma, with each subunit contributing to the functional channel pore. The subunit stoichiometry of ENaC remains uncertain with electrophysiology and biochemical experiments supporting both a tetramer with a 2alpha:1beta:1gamma stoichiometry and a higher ordered channel with a 3alpha:3beta:3gamma stoichiometry. Here we used an independent biophysical approach based upon fluorescence resonance energy transfer (FRET) between differentially fluorophore-tagged ENaC subunits to determine the subunit composition of mouse ENaC functionally reconstituted in Chinese hamster ovary and COS-7 cells. We found that when all three subunits were co-expressed, ENaC contained at least two of each type of subunit. Findings showing that ENaC subunits interact with similar subunits in immunoprecipitation studies are consistent with these FRET results. Upon native polyacrylamide gel electrophoresis, moreover, oligomerized ENaC runs predominantly as a single species with a molecular mass of >600 kDa. Because single ENaC subunits have a molecular mass of approximately 90 kDa, these results also agree with the FRET results. The current results as a whole, thus, are most consistent with a higher ordered channel possibly with a 3alpha:3beta:3gamma stoichiometry.     

On the evocability of a positive oestrogen feedback action on LH secretion in transsexual men and women.

In transsexual men with homosexual behaviour and intact testicular function, as well as in homosexual men with normal gender identity, following a negative oestrogen feedback effect a delayed positive oestrogen feedback action on LH secretion was evoked. By contrast, in transsexual men with hypo- or asexuality and intact testes or hypergonadotrophic hypo- or agonadism, as well as in heterosexual men with normal gender identity, a negative oestrogen feedback effect was not followed by a positive feedback action on LH release. In transsexual women with homosexual behaviour and oligo- and/or hypomenorrhoea, only a weak or at best moderate positive oestrogen feedback action on LH release was evocable, similarly as in castrated and oestrogen-primed heterosexual men. By contrast, in a transsexual woman with bisexual behaviour and eumenorrhoea, a strong positive oestrogen feedback action on LH secretion was evocable, as well as in heterosexual women with normal gender identity.     

High-affinity Ca(2+)- and substrate-binding sites on protein kinase C alpha as determined by nuclear magnetic resonance spectroscopy.

Water proton nuclear magnetic resonance (NMR) relaxation rates were used to identify metal sites on protein kinase C (PKC) isozymes alpha and beta using paramagnetic Gd3+ as a probe. The paramagnetic effect of Gd3+ on water proton relaxation was enhanced with PKC isozymes alpha and beta in the presence of diheptanoylphosphatidylcholine/1,2-dioleoyl-sn-glycerol (PC7/DO). The data are consistent with a single class of metal-binding sites on PKC beta and two classes of sites on PKC alpha: a single high-affinity site with a KD for Gd3+ of 0.2 microM and a larger class of sites with a lower affinity for Gd3+. Titration with Ca2+ abolished the observed enhancement of water proton relaxation by the PKC alpha.Gd3+ complex, consistent with displacement of Gd3+ by Ca2+. Titrations of the PKC alpha.Gd3+ complex with Co(NH3)4ATP, a substitution-inert analogue of ATP, caused a substantial decrease in the observed water proton relaxation enhancement, consistent with formation of a ternary enzyme.metal.substrate complex with a KPKC alpha.Gd.[CoATP] of 30-100 nM. Titration of the metal enzyme complex with a model peptide substrate derived from the pseudosubstrate sequence of PKC alpha caused a similar decrease in enhancement at stoichiometric concentrations consistent with the formation of a PKC alpha.Gd3+.peptide complex with a KPKC alpha.Gd.[peptide] of less than or equal to 13 nM. Titrations of the fully formed PKC alpha.Gd3+.peptide complex with Co(NH3)4ATP caused a further decrease in enhancement consistent with formation of a quaternary complex.(ABSTRACT TRUNCATED AT 250 WORDS)     

Excitation of waves in an inhomogeneous plasma

The evolution of initial perturbations in a spatially inhomogeneous cold electron plasma in the absence of an external magnetic field is considered. The excitation of both continuous-spectrum bulk plasma waves and surface plasma waves with a discrete frequency spectrum is investigated. Analytic solutions are obtained in the long-wavelength limit, and the excitation of waves of arbitrary length is analyzed numerically. The local, integral, and spatial spectra are calculated, as well as the field structures and dispersion properties of waves in waveguides filled nonuniformly with a plasma. It is shown that, in a plasma with a smooth boundary, there also exist surface waves with a discrete spectrum (although with somewhat different properties as compared to those in a plasma with a sharp boundary), which are excited together with continuous-spectrum bulk waves during the evolution of the initial perturbation.     

Repetitive mating and female fitness in Dysdercus cardinalis (Hemiptera: Pyrrhocoridae)

Using three mating-treatment groups–pairing with a male for life, pairing with a male from adult emergence to first oviposition, and no pairing (virgin)–of Dysdercus cardinalis females in a laboratory study, the following results were obtained. Most of the virgin females did not lay eggs; those that did oviposited for the first time at a considerably older age than females in the other two groups. In a lifetime, females pairing with a male for life and those pairing with a male up to first oviposition produced essentially the same number of eggs, and this was more than 3.5 times the number of eggs laid by a virgin female. Virgin females produced an average of 1.3 clutches in a lifetime, compared with about 4.5 clutches produced by females in the other two groups. Reproductive span was significantly shorter, and fecundity per day of reproductive span significantly greater, for females pairing with males for life than for those pairing with a male up to first oviposition. Age at death was significantly different amongst females in different mating-treatment groups. Virgin females had the longest life, followed by females pairing with a male up to first oviposition and females pairing with a male for life, in that order. There was a positive correlation between lifetime gross reproduction and age at death for females pairing with a male for life. There was no relationship between these two characters for females pairing with a male up to first oviposition. Both females pairing with a male for life and those pairing with a male to first oviposition exhibited a significant inverse relationship between fecundity per day and age at death. The results obtained indicate that (1) mating is a prerequisite for normal gonadal activity in Dysdercus cardinalis , and (2) repetitive mating increases the rate of reproduction. This would reduce the mean age of parenthood which is inversely related to the intrinsic rate of increase.     

Prostacyclin degradation in patients with quantitative platelet disorders

Plasma prostacyclin (PGI2) degradation rates were measured at 1, 5, 15 and 30 min in a group of patients with platelet quantitative disorders of various pathogeneses, including 13 with thrombocytosis, 16 with thrombocytopenia from impaired production in the bone marrow, 11 with thrombocytopenia from peripheral destruction, and 28 normal, healthy persons. Patients with thrombocytosis had a low PGI2 degradation rate, whereas patients with thrombocytopenia due to impaired production had a high PGI2 degradation rate. Of the patients with thrombocytopenia caused by peripheral destruction, six with idiopathic thrombocytopenia purpura (ITP) had a slow PGI2 degradation in contrast to five with systemic lupus erythematosus (SLE) - four concurrently had cryoglobulinemia - who had a rapid PGI2 degradation. The findings suggest that: (1) a platelet-derived substance in the human plasma may have a PGI2 stabilising activity; (2) presence of cryoglobulin or immune complex in plasma may interfere with PGI2 stability.     

Topological analysis of chaos in a three-variable biochemical model

A three-variable biochemical prototype involving two enzymes with autocatalytic regulation proposed by Decroly and Goldbeter (1987) is analyzed using a topological approach. A two-branched manifold, a so-called template, is thus identified. For certain control parameter values, this template is a horseshoe template with a global torsion of two half-turns. This implies that the bifurcation diagram can be described using the usual sequences associated with a unimodal map with a differentiable maximum as well as exemplified by the logistic map. Moreover, a type-I intermittency associated with a saddle-node bifurcation is exhibited. The dynamics from a single time series are also investigated to determine whether it is possible to investigate the dynamics of this biochemical model from the measure of a single concentration.