Spatial working memory and hippocampal size across pregnancy in rats

The present experiments investigated the effects of pregnancy on performance in the Morris water maze and on hippocampal volume. In the first study, pregnant rats (in between the first and second trimester) outperformed nonpregnant rats on the Morris water maze on 1 day of testing. In the second study, rats were tested in a working memory variation of the maze in which the spatial location of the platform varied. Pregnant females traveled shorter distances than nonpregnant females during the first two trimesters, but performed worse than nonpregnant females during the third trimester. Latency measures showed a similar profile. Group differences in performance were not related to changes in swim speed. However, changes in performance in pregnant females may be related to estrogen, progesterone, and/or corticosterone levels during pregnancy, with low levels of estradiol and high levels of progesterone being associated with better performance. There were no significant differences between pregnant and nonpregnant animals on any of the brain measures, although pregnant animals tended to have a smaller hippocampus than nonpregnant animals. These results indicate that pregnancy can affect performance, possibly related to the hormonal changes that accompany pregnancy.     

Extended Survival and Persistence of Campylobacter spp. in Water and Aquatic Biofilms and Their Detection by Immunofluorescent-Antibody and -rRNA Staining

In water microcosm experiments, the survival times of Campylobacter isolates differed by up to twofold, as determined by culturing; this difference increased to fourfold when particular combinations of temperature and oxygenation were used. The mean survival times were much longer at 4 and 10°C (202 and 176 h, respectively) than at 22 and 37°C (43 and 22 h, respectively). The influence of anaerobiosis on survival time was less dramatic and differed considerably between isolates. In a two-stage water distribution model preparation containing a biofilm consisting of standardized autochthonous water microflora, Campylobacter isolates continued to differ in survival time. However, the survival times of cultures were considerably longer in the presence of the autochthonous water microflora (strains CH1 and 9752 survived 700 and 360 h, respectively, at 4°C) than in the sterile microcosms (strains CH1 and 9752 survived 230 and 157 h, respectively). Although increased temperature and oxygenation were generally detrimental to culturability, the interaction of these two factors influenced the two strains examined differently. When the organisms were grown aerobically at 30°C, the survival of the two strains was reversed; aerobiosis decreased the survival time of strain CH1 by 30%, but unexpectedly improved the persistence time of strain 9752 by more than threefold. Persistence times within biofilms were much longer when they were determined by detection methods not involving culturing. Immunofluorescent-antibody staining demonstrated that the pathogen persisted up to the termination of the experiments after 28 and 42 days of incubation at 30 and 4°C, respectively. The specificity of detection within intact biofilms was reduced because of high background fluorescence. However, preliminary studies with a Campylobacter-specific rRNA probe revealed the same extended persistence of the pathogen within the biofilms.     

Organization and mechanical behaviour of myocyte–ligament composites in a sea-urchin lantern: the compass depressors of Stylocidaris affinis (Echinodermata, Echinoida)

 Certain components of the jaw apparatus, or lantern, of regular sea-urchins form a ’compass system’ the function of which has still to be established. This system includes ten compass depressors (CDs) which connect the compass ossicles to the inner edge of the test. Previous studies focused on the CDs of euechinoid sea-urchins. This paper provides the first detailed account of the organization and mechanical behaviour of the CDs of a cidaroid sea-urchin, Stylocidaris affinis. The outermost layer of its CDs is a coelothelium comprising apical peritoneocytes, sparse subapical myocytes and two types of granule-containing cells. The central core of the CD is dominated by longitudinally orientated collagen fibrils arranged in bundles surrounded by networks of beaded microfibrils. Myocytes are scattered throughout the core and are always surrounded by a basal lamina which usually encloses the same two types of granule-containing cells observed in the coelothelium. Each CD is attached to the outer coelomic septum by a mesentery, both the connective tissue and coelothelia of which lack myocytes and granule-containing cells. From data on the relationship between the vertical position of the lantern and the passive and active forces developed by intact CD sets, it appears that the CDs resist elevation of the lantern above its ’resting position’ and that they develop a maximal contractile force when their length corresponds to that at the resting position. The connective tissue of the CDs has the capacity to undergo nervously mediated changes in stretch resistance, although this is expressed more weakly than in the euechinoid CDs. These results are related to current views on the physiological role of the compass system. Accepted: 15 March 1998     

Recombinant Expression, Purification, and Characterization of Three Isoenzymes of Aspartate Aminotransferase fromArabidopsis thaliana

Five different genes encoding isoenzymes of aspartate aminotransferase (AAT) have been identified in the plantArabidopsis thaliana.cDNA sequences encoding three of these AAT isoenzymes,asp1(mitochondrial),asp2(cytosolic), andasp5(plastid), were manipulated into bacterial expression vectors and the recombinant proteins expressed were purified from liquid culture using conventional methods. Yields of the purified isoenzymes varied from 11.5 mg/g wet wt cells (AAT5) to 0.95 mg/g wet wt cells (AAT2), an improvement of more than 1000-fold over typical yields of native isoenzymes obtained from plant tissues of other species. Analysis of the recombinant proteins on denaturing PAGE gels indicated subunitM_rs of between 44 and 45 K. Kinetic parameters (K_mandk_cat) obtained for all four substrates (aspartate, α-ketoglutarate, glutamate, and oxaloacetate) were consistent with values obtained for native AAT isoenzymes from other plant species. Further characterization of the purified recombinant enzymes alongside native enzymes fromA. thalianaleaf tissue on AAT activity gels confirmed the identity ofasp1andasp2as the mitochondrial and cytosolic AAT genes but indicated thatasp5may encode an amyloplastic rather than the chloroplastic enzyme.     

Mechanical properties of sea-urchin lantern muscles: a comparative investigation of intact muscle groups in Paracentrotus lividus (Lam.) and Stylocidaris affinis (Phil.) (Echinodermata, Echinoidea)

The jaw apparatus, or lantern, of sea-urchins contains five pairs of retractor and protractor muscles which are responsible for lantern displacement. Using intact retractor or protractor groups, the force-length relations of these muscles were compared in two taxonomically distant species, Paracentrotus lividus and Stylocidaris affinis. The total contractile forces generated by the muscles can be resolved into vertical and horizontal components. It was found that the vertical component of the retractors is maximal at a lantern position which is significantly lower (i.e. more protruded) in Paracentrotus than in Stylocidaris. Total forces generated by the retractors were in both species maximal at or above the lantern `resting positions'. In Paracentrotus alone, the total force-displacement curves tended to be bimodal. It is hypothesized that the retractors of Paracentrotus contain two populations of muscle fibres, one adapted for jaw opening and one for lantern retraction. No significant differences in the properties of the protractors of the two species could be identified. The lantern of Paracentrotus is more mobile than that of Stylocidaris and is able to exploit a wider range of food sources. This investigation has shown that the force-length relations of the lantern muscles match their differing working conditions. Accepted: 3 November 1997     

Density, dispersal, and feeding impact of western flower thrips (Thysanoptera: Thripidae) on flowering chrysanthemum at different spatial scales

Abstract.  1. This study evaluated the effect of dispersal on the density and feeding impact of a phytophagous insect in relation to the spatial distribution of its host plants.
2. The interaction between density, dispersal, and feeding impact of western flower thrips on flowering chrysanthemum was quantified at three spatial scales, with infested and uninfested plants either isolated in 0.25 m² individual cages, or enclosed together in 2.25 m² communal cages or 75 m² greenhouses.
3. In individual cages, the rate of dispersal from chrysanthemum plants to blue sticky traps increased with the density of thrips for females but not males. Uninfested plants consistently had fewer thrips when they were individually caged rather than enclosed with plants infested with adults, indicating that dispersal mediates inter-plant distribution of thrips.
4. The feeding impact of thrips on inflorescences was evaluated using the absorbance of ethanol extracts at wavelengths characteristic of yellow carotenoid pigments associated with chrysanthemum inflorescences (415, 445, and 472 nm). Increasing absorbance of extracts with increasing density of thrips per inflorescence suggests that feeding by thrips results in ruptured cells leaching carotenoid pigments.
5. In communal cages, the distribution of thrips was uniform for infested and uninfested plants, whereas the density and feeding impact of thrips in greenhouses were higher for infested than uninfested plants. These results suggest that short-range dispersal by adults homogenises the density and feeding impact of thrips among host plants only on a small spatial scale.     

A Phase I Double Blind,Placebo-Controlled,Randomized Study of the Safety and Immunogenicity of an Adjuvanted HIV-1 Gag-Pol-Nef Fusion Protein and Adenovirus 35 Gag-RT-Int-Nef Vaccine in Healthy HIV-Uninfected African Adults

Background

Sequential prime-boost or co-administration of HIV vaccine candidates based on an adjuvanted clade B p24, RT, Nef, p17 fusion protein (F4/AS01) plus a non-replicating adenovirus 35 expressing clade A Gag, RT, Int and Nef (Ad35-GRIN) may lead to a unique immune profile, inducing both strong T-cell and antibody responses.

Methods

In a phase 1, double-blind, placebo-controlled trial, 146 healthy adult volunteers were randomized to one of four regimens: heterologous prime-boost with two doses of F4/AS01_E or F4/AS01_B followed by Ad35-GRIN; Ad35-GRIN followed by two doses of F4/AS01_B; or three co-administrations of Ad35-GRIN and F4/AS01_B. T cell and antibody responses were measured.

Results

The vaccines were generally well-tolerated, and did not cause serious adverse events. The response rate, by IFN-γ ELISPOT, was greater when Ad35-GRIN was the priming vaccine and in the co-administration groups. F4/AS01 induced CD4+ T-cells expressing primarily CD40L and IL2 +/- TNF-α, while Ad35-GRIN induced predominantly CD8+ T-cells expressing IFN-γ +/- IL2 or TNF-α. Viral inhibition was induced after Ad35-GRIN vaccination, regardless of the regimen. Strong F4-specific antibody responses were induced. Immune responses persisted at least a year after the last vaccination. The complementary response profiles, characteristic of each vaccine, were both expressed after co-administration.

Conclusion

Co-administration of an adjuvanted protein and an adenovirus vector showed an acceptable safety and reactogenicity profile and resulted in strong, multifunctional and complementary HIV-specific immune responses.

Trial Registration

ClinicalTrials.gov NCT01264445     

Feedback Valence Affects Auditory Perceptual Learning Independently of Feedback Probability

Previous studies have suggested that negative feedback is more effective in driving learning than positive feedback. We investigated the effect on learning of providing varying amounts of negative and positive feedback while listeners attempted to discriminate between three identical tones; an impossible task that nevertheless produces robust learning. Four feedback conditions were compared during training: 90% positive feedback or 10% negative feedback informed the participants that they were doing equally well, while 10% positive or 90% negative feedback informed them they were doing equally badly. In all conditions the feedback was random in relation to the listeners’ responses (because the task was to discriminate three identical tones), yet both the valence (negative vs. positive) and the probability of feedback (10% vs. 90%) affected learning. Feedback that informed listeners they were doing badly resulted in better post-training performance than feedback that informed them they were doing well, independent of valence. In addition, positive feedback during training resulted in better post-training performance than negative feedback, but only positive feedback indicating listeners were doing badly on the task resulted in learning. As we have previously speculated, feedback that better reflected the difficulty of the task was more effective in driving learning than feedback that suggested performance was better than it should have been given perceived task difficulty. But contrary to expectations, positive feedback was more effective than negative feedback in driving learning. Feedback thus had two separable effects on learning: feedback valence affected motivation on a subjectively difficult task, and learning occurred only when feedback probability reflected the subjective difficulty. To optimize learning, training programs need to take into consideration both feedback valence and probability.     

Improving Child Oral Health: Cost Analysis of a National Nursery Toothbrushing Programme

Dental caries is one of the most common diseases of childhood. The aim of this study was to compare the cost of providing the Scotland-wide nursery toothbrushing programme with associated National Health Service (NHS) cost savings from improvements in the dental health of five-year-old children: through avoided dental extractions, fillings and potential treatments for decay.

Methods

Estimated costs of the nursery toothbrushing programme in 2011/12 were requested from all Scottish Health Boards. Unit costs of a filled, extracted and decayed primary tooth were calculated using verifiable sources of information. Total costs associated with dental treatments were estimated for the period from 1999/00 to 2009/10. These costs were based on the unit costs above and using the data of the National Dental Inspection Programme and then extrapolated to the population level. Expected cost savings were calculated for each of the subsequent years in comparison with the 2001/02 dental treatment costs. Population standardised analysis of hypothetical cohorts of 1000 children per deprivation category was performed.

Results

The estimated cost of the nursery toothbrushing programme in Scotland was £1,762,621 per year. The estimated cost of dental treatments in the baseline year 2001/02 was £8,766,297, while in 2009/10 it was £4,035,200. In 2002/03 the costs of dental treatments increased by £213,380 (2.4%). In the following years the costs decreased dramatically with the estimated annual savings ranging from £1,217,255 in 2003/04 (13.9% of costs in 2001/02) to £4,731,097 in 2009/10 (54.0%). Population standardised analysis by deprivation groups showed that the largest decrease in modelled costs was for the most deprived cohort of children.

Conclusions

The NHS costs associated with the dental treatments for five-year-old children decreased over time. In the eighth year of the toothbrushing programme the expected savings were more than two and a half times the costs of the programme implementation.