Small angle X-ray scattering as a high-throughput method to classify antimicrobial modes of action.

Multi-drug resistant bacteria are currently undermining our health care system worldwide. While novel antimicrobial drugs, such as antimicrobial peptides, are urgently needed, identification of new modes of action is money and time consuming, and in addition current approaches are not available in a high throughput manner. Here we explore how small angle X-ray scattering (SAXS) as high throughput method can contribute to classify the mode of action for novel antimicrobials and therefore supports fast decision making in drug development. Using data bases for natural occurring antimicrobial peptides or predicting novel artificial peptides, many candidates can be discovered that will kill a selected target bacterium. However, in order to narrow down the selection it is important to know if these peptides follow all the same mode of action. In addition, the mode of action should be different from conventional antibiotics, in consequence peptide candidates can be developed further into drugs against multi-drug resistant bacteria. Here we used one short antimicrobial peptide with unknown mode of action and compared the ultrastructural changes of Escherichia coli cells after treatment with the peptide to cells treated with classic antibiotics. The key finding is that SAXS as a structure sensitive tool provides a rapid feedback on drug induced ultrastructural alterations in whole E. coli cells. We could demonstrate that ultrastructural changes depend on the used antibiotics and their specific mode of action. This is demonstrated using several well characterized antimicrobial compounds and the analysis of resulting SAXS curves by principal component analysis. To understand the result of the PCA analysis, the data is correlated with TEM images. In contrast to real space imaging techniques, SAXS allows to obtain nanoscale information averaged over approximately one million cells. The measurement takes only seconds, while conventional tests to identify a mode of action require days or weeks per single substance. The antimicrobial peptide showed a different mode of action as all tested antibiotics including polymyxin B and is therefore a good candidate for further drug development. We envision SAXS to become a useful tool within the high-throughput screening pipeline of modern drug discovery. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert.

1H, 15N and 13C assignment of the amyloidogenic protein medin using fast-pulsing NMR techniques.

Thirty-one proteins are known to form extracellular fibrillar amyloid in humans. Molecular information about many of these proteins in their monomeric, intermediate or fibrillar form and how they aggregate and interact to form the insoluble fibrils is sparse. This is because amyloid proteins are notoriously difficult to study in their soluble forms, due to their inherent propensity to aggregate. Using recent developments in fast NMR techniques, band-selective excitation short transient and band-selective optimized flip-angle short-transient heteronuclear multiple quantum coherence we have been able to assign a 5 kDa full-length amyloidogenic protein called medin. Medin is the key protein component of the most common form of localised amyloid with a proposed role in aortic aneurysm and dissection. This assignment will now enable the study of the early interactions that could influence initiation and progression of medin aggregation. The chemical shifts have been deposited in the BioMagRes-Bank accession Nos. 25399 and 26576.

Multiple spine boutons are formed after long-lasting LTP in the awake rat.

The formation of multiple spine boutons (MSBs) has been associated with cognitive abilities including hippocampal-dependent associative learning and memory. Data obtained from cultured hippocampal slices suggest that the long-term maintenance of synaptic plasticity requires the formation of new synaptic contacts on pre-existing synapses. This postulate however, has never been tested in the awake, freely moving animals. In the current study, we induced long-term potentiation (LTP) in the dentate gyrus (DG) of awake adult rats and performed 3-D reconstructions of electron micrographs from thin sections of both axonal boutons and dendritic spines, 24 h post-induction. The specificity of the observed changes was demonstrated by comparison with animals in which long-term depression (LTD) had been induced, or with animals in which LTP was blocked by an N-methyl-D-aspartate (NMDA) antagonist. Our data demonstrate that whilst the number of boutons remains unchanged, there is a marked increase in the number of synapses per bouton 24 h after the induction of LTP. Further, we demonstrate that this increase is specific to mushroom spines and not attributable to their division. The present investigation thus fills the gap existing between behavioural and in vitro studies on the role of MSB formation in synaptic plasticity and cognitive abilities.

Republished paper: assessment of doctors' consultation skills in the paediatric setting: the Paediatric Consultation Assessment Tool.

OBJECTIVE: To determine the utility of a novel Paediatric Consultation Assessment Tool (PCAT). DESIGN: Developed to measure clinicians' communication behaviour with children and their parents/guardian, PCAT was designed according to consensus guidelines and refined at a number of stages. Volunteer clinicians provided videotaped real consultations. Assessors were trained to score communication skills using PCAT, a novel rating scale. SETTING: Eight UK paediatric units. PARTICIPANTS: 19 paediatricians collected video-recorded material; a second cohort of 17 clinicians rated the videos. MAIN OUTCOME MEASURES: Itemised and aggregated scores were analysed (means and 95% confidence intervals) to determine measurement characteristics and relationship to patient, consultation, clinician and assessor attributes; generalisability coefficient of aggregate score; factor analysis of items; comparison of scores between groups of patients, consultations, clinicians and assessors. RESULTS: 188 complete consultations were analysed (median per doctor = 10). 3 videos marked by any trained assessor are needed to reliably (r > 0.8) assess a doctor's triadic consultation skills using PCAT, 4 to assess communication with just children or parents. Performance maps to two factors - "clinical skills" and "communication behaviour"; clinicians score more highly on the former (mean (SD) 95% CI 0.52 (0.075)). There were significant differences in scores for the same skills applied to parent and child, especially between the ages of 2 and 10 years, and for information-sharing rather than relationship building skills (2-tailed significance < 0.001). Conclusions The PCAT appears to be reliable, valid and feasible for the assessment of triadic consultation skills by direct observation.

A subpopulation of serotonin 1B receptors colocalize with the AMPA receptor subunit GluR2 in the hippocampal dentate gyrus.

The serotonin(1B) receptor (5-HT(1B)R) plays a role in cognitive processes that also involve glutamatergic neurotransmission via amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) receptors. Accumulating experimental evidence also highlights the involvement of 5-HT(1B)Rs in several neurological disorders. Consequently, the 5-HT(1B)R is increasingly implicated as a potential therapeutic target for intervention in cognitive dysfunction. Within the hippocampus, a brain region critical to cognitive processing, populations of pre- and post-synaptic 5-HT(1B)Rs have been identified. Thus, 5-HT(1B)Rs could have a role in the modulation of hippocampal pre- and post-synaptic conductance. Previously, we demonstrated colocalization of 5-HT(1B)Rs with the N-methyl-D-aspartate (NMDA) receptor subunit NR1 in a subpopulation of granule cell dendrites (Peddie et al. [53]). In this study, we have examined the cellular and subcellular distribution of 5-HT(1B)Rs with the AMPA receptor subunit GluR2. Of 5-HT(1B)R positive profiles, 28% displayed colocalization with GluR2. Of these, 87% were dendrites, corresponding to 41% and 10% of all 5-HT(1B)R labeled or GluR2 labeled dendrites, respectively. Dendritic labeling was both cytoplasmic and membranous but was not usually associated with synaptic sites. Colocalization within dendritic spines and axons was comparatively rare. These findings indicate that within the dentate gyrus molecular layer, dendritic 5-HT(1B)Rs are expressed predominantly on GluR2 negative granule cell processes. However, a subpopulation of 5-HT(1B)Rs is expressed on GluR2 positive dendrites. Here, it is suggested that activation of the 5-HT(1B)R may play a role in the modulation of AMPA receptor mediated conductance, further supporting the notion that the 5-HT(1B)R represents an interesting therapeutic target for modulation of cognitive function.

Alterations in synaptic curvature in the dentate gyrus following induction of long-term potentiation, long-term depression, and treatment with the N-methyl-D-aspartate receptor antagonist CPP.

Alterations in curvature of the post synaptic density (PSD) and apposition zone (AZ), are believed to play an important role in determining synaptic efficacy. In the present study we have examined curvature of PSDs and AZs 24 h following homosynaptic long-term potentiation (LTP), and heterosynaptic long-term depression (LTD) in vivo, in awake adult rats. High frequency stimulation (HFS) applied to the medial perforant path to the dentate gyrus induced LTP while HFS stimulation of the lateral perforant path induced LTD in the middle molecular layer of the dentate gyrus (DG). Curvature changes were analysed in this area using three dimensional (3-D) reconstructions of electron microscope images of ultrathin serial sections. Very large and significant changes in 3-D measurements of AZ and PSD curvature occurred 24 h following both LTP and LTD, with a flattening of the normal concavity of mushroom spine heads and a change to convexity for thin spines. An N-methyl-D-aspartate (NMDA) receptor antagonist CPP (3-[(R)-2-Carboxypiperazin-4-yl]-propyl-1-phosphonic acid) blocked the changes in curvature of mushroom and thin spine PSDs and apposition zones, actually increasing the concavity of mushroom spines as the spine engulfed the presynaptic bouton. In order to establish whether these changes resulted from the effect of the NMDA antagonist or from its coincidence with synaptic activation during testing we examined the effects of CPP alone on PSD and apposition zone curvature. It was found that CPP alone also caused a small decrease in curvature of both PSD and apposition zone of mushroom and thin spines.

The N-methyl-D-aspartate receptor antagonist CPP alters synapse and spine structure and impairs long-term potentiation and long-term depression induced morphological plasticity in dentate gyrus of the awake rat.

Long-term morphological synaptic changes associated with homosynaptic long-term potentiation (LTP) and heterosynaptic long-term depression (LTD) in vivo, in awake adult rats were analyzed using three-dimensional (3-D) reconstructions of electron microscope images of ultrathin serial sections from the molecular layer of the dentate gyrus. For the first time in morphological studies, the specificity of the effects of LTP and LTD on both spine and synapse ultrastructure was determined using an N-methyl-d-aspartate (NMDA) receptor antagonist CPP (3-[(R)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid). There were no differences in synaptic density 24 h after LTP or LTD induction, and CPP alone had no effect on synaptic density. LTP increased significantly the proportion of mushroom spines, whereas LTD increased the proportion of thin spines, and both LTP and LTD decreased stubby spine number. Both LTP and LTD increased significantly spine head evaginations (spinules) into synaptic boutons and CPP blocked these changes. Synaptic boutons were smaller after LTD, indicating a pre-synaptic effect. Interestingly, CPP alone decreased bouton and mushroom spine volumes, as well as post-synaptic density (PSD) volume of mushroom spines.These data show similarities, but also some clear differences, between the effects of LTP and LTD on spine and synaptic morphology. Although CPP blocks both LTP and LTD, and impairs most morphological changes in spines and synapses, CPP alone was shown to exert effects on aspects of spine and synaptic structure.

Assessment of doctors' consultation skills in the paediatric setting: the Paediatric Consultation Assessment Tool.

OBJECTIVE: To determine the utility of a novel Paediatric Consultation Assessment Tool (PCAT). DESIGN: Developed to measure clinicians' communication behaviour with children and their parents/guardian, PCAT was designed according to consensus guidelines and refined at a number of stages. Volunteer clinicians provided videotaped real consultations. Assessors were trained to score communication skills using PCAT, a novel rating scale. SETTING: Eight UK paediatric units. PARTICIPANTS: 19 paediatricians collected video-recorded material; a second cohort of 17 clinicians rated the videos. MAIN OUTCOME MEASURES: Itemised and aggregated scores were analysed (means and 95% confidence intervals) to determine measurement characteristics and relationship to patient, consultation, clinician and assessor attributes; generalisability coefficient of aggregate score; factor analysis of items; comparison of scores between groups of patients, consultations, clinicians and assessors. RESULTS: 188 complete consultations were analysed (median per doctor = 10). 3 videos marked by any trained assessor are needed to reliably (r>0.8) assess a doctor's triadic consultation skills using PCAT, 4 to assess communication with just children or parents. Performance maps to two factors--"clinical skills" and "communication behaviour"; clinicians score more highly on the former (mean (SD) 95% CI 0.52 (0.075)). There were significant differences in scores for the same skills applied to parent and child, especially between the ages of 2 and 10 years, and for information-sharing rather than relationship-building skills (2-tailed significance <0.001). CONCLUSIONS: The PCAT appears to be reliable, valid and feasible for the assessment of triadic consultation skills by direct observation.

Partial kindling induces neurogenesis, activates astrocytes and alters synaptic morphology in the dentate gyrus of freely moving adult rats.

A partial kindling procedure was used to investigate the correlation between focal seizure development and changes in dendritic spine morphology, ongoing neurogenesis and reactive astrogliosis in the adult rat dentate gyrus (DG). The processes of neurogenesis and astrogliosis were investigated using markers for doublecortin (DCX), 5-bromo-2-deoxyuridine (BrdU) and glial fibrillary acidic protein (GFAP). Our data demonstrate that mild focal seizures induce a complex series of cellular events in the DG one day after cessation of partial rapid kindling stimulation consisting (in comparison to control animals that were electrode implanted but unkindled), firstly, of an increase in the number of postmitotic BrdU labeled cells, and secondly, an increase in the number of DCX labeled cells, mainly in subgranular zone. Ultrastructural changes were examined using qualitative electron microscope analysis and 3-D reconstructions of both dendritic spines and postsynaptic densities. Typical features of kindling in comparison to control tissue included translocation of mitochondria to the base of the dendritic spine stalks; a migration of multivesicular bodies into mushroom dendritic spines, and most notably formation of "giant" spinules originating from the head of the spines of DG neurons. These morphological alterations arise at seizure stages 2-3 (focal seizures) in the absence of signs of the severe generalized seizures that are generally recognized as potentially harmful for neuronal cells. We suggest that an increase in ongoing neurogenesis, reactive astrogliosis and dendritic spine reorganization in the DG is the crucial step in the chain of events leading to the progressive development of seizure susceptibility in hippocampal circuits.

Dendritic colocalisation of serotonin1B receptors and the glutamate NMDA receptor subunit NR1 within the hippocampal dentate gyrus: an ultrastructural study.

The serotonin1B receptor (5-HT1BR) plays a significant role in cognitive processing, which also involves glutamatergic transmission via N-methyl-D-aspartate (NMDA) receptors. It is implicated in a range of disorders, many of which also have a cognitive component, and therefore represents a valuable therapeutic target. 5-HT1BRs are described as predominantly pre-synaptic auto- and/or hetero-receptors, modulating the release of neurotransmitters including glutamate. However, a detailed assessment of localisation within the hippocampus, a pivotal structure in cognitive processing, has been absent. Here, we have conducted an electron microscopic examination of the subcellular distribution of the 5-HT1BR, NMDA receptor subunit NR1 and neurotransmitter gamma-aminobutyric acid (GABA), within the hippocampal dentate gyrus. Ultrastructurally, 18% of 5-HT1BR immunoreactivity was pre-synaptic (within axons and axon terminals), and 65% post-synaptic (within dendrites and dendritic spines); no significant differences were found between molecular layer subdivisions. Post-synaptic labelling was cytoplasmic and membranous. Spinous labelling was more frequently bound to the plasma membrane, but not usually directly associated with the synaptic specialisation. Only 16% of 5-HT1BR positive profiles displayed NR1 labelling, of which most were dendrites, at a slightly higher level within the inner, compared to middle and outer molecular layer divisions. 5-HT1BR labelled profiles rarely showed labelling for GABA. These findings indicate that within the dentate gyrus, pre-synaptic 5-HT1BRs may modulate non-GABAergic neurotransmitter release whilst post-synaptic 5-HT1BRs are expressed on segments of mainly NR1 negative granule cell processes. However, a subpopulation of 5-HT1BRs is expressed on NR1 positive dendrites. Here, the 5-HT1BR may be an interesting target for modulation of NMDA receptor mediated currents.

Colocalisation of serotonin2A receptors with the glutamate receptor subunits NR1 and GluR2 in the dentate gyrus: an ultrastructural study of a modulatory role.

The serotonin(2A) receptor (5-HT(2A)R) is implicated in many neurological disorders and has a role in cognitive processes, reliant upon hippocampal glutamate receptors. Recent studies show that 5-HT(2A)R agonists and/or antagonists can influence cognitive function, suggesting a critical hippocampal role for these receptors, yet their cellular and subcellular distribution within this region has not been comprehensively analysed. Here, we have conducted an electron microscopic examination of 5-HT(2A)R distribution with the glutamate N-methyl-D-aspartate (NMDA) and amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) receptor subunits NR1 and GluR2 in the hippocampal dentate gyrus (DG) in order to investigate whether 5-HT(2A)R location is compatible with a modulatory role over NMDA and/or AMPA receptor mediated neurotransmission. Of 5-HT(2A)R positive profiles, 56% were dendrites and 16% were dendritic spines. Labelling was both cytoplasmic and membranous. Spinous labelling was more frequently membranous at peri- and extra-synaptic sites, though was also associated with synaptic specialisations. Profiles displaying colocalisation of immunoreactivity for 5-HT(2A)Rs with NR1 or GluR2 were predominantly dendrites, representing 11% and 8% of 5-HT(2A)R positive profiles, respectively. Additionally, 12% of 5-HT(2A)R labelled profiles also displayed immunoreactivity for gamma-aminobutyric acid (GABA). These data indicate most 5-HT(2A)Rs are expressed on granule cell projections, with a smaller subpopulation expressed on GABAergic interneurons.

ARG3.1/ARC expression in hippocampal dentate gyrus astrocytes: ultrastructural evidence and co-localization with glial fibrillary acidic protein.

Synaptic efficacy following long-term potentiation (LTP) and memory consolidation is associated with changes in the expression of immediate early genes (IEGs). These changes are often accompanied by increased expression of glial fibrillary acidic protein (GFAP). While the protein products of the majority of IEGs are mainly restricted to the cell body, Arg3.1/Arc product is rapidly delivered to dendrites, where it accumulates close to synaptic sites. Arg3.1/Arc protein was originally considered neurone specific; however, we have recently found Arg3.1/Arc immunoreactivity (Arg3.1/Arc-IR) within glial cells and demonstrated its increased expression after LTP in the hippocampal dentate gyrus (DG). Here, we have further investigated this novel finding, using electron microscopic immunocytochemistry to determine the localization and sub-cellular distribution of Arg3.1/Arc protein in GFAP positive glia (GFAP-IR) in the DG. Arg3.1/Arc labelling was seen prominently in GFAP-IR glial cell bodies and in large- and medium-sized glial filamentous processes. GFAP-labelled medium-small peri-synaptic glial profiles also displayed Arg3.1/Arc-IR; however, the very thin and distal glial filaments only displayed Arc-IR. Arc-IR was distributed throughout the cytoplasm, often associated with GFAP filaments, and along the plasma membrane of glial processes. Peri-synaptic glial Arg3.1/Arc-IR processes were apposed to pre- and/or post-synaptic profiles at asymmetric axospinous synapses. These data, taken with our earlier study which provided evidence for an increase in astrocytic Arg3.1/Arc-IR after the induction of LTP, suggest a role for glial Arg3.1/Arc in structural and synaptic plasticity which may be critical for the maintenance of cognitive functions.

Prevalence and consequences of androgen deficiency in young male cancer survivors in a controlled cross-sectional study.

BACKGROUND: Testosterone replacement in hypogonadal males improves body composition, sexual function, and health-related quality of life. Male cancer survivors are at risk of androgen deficiency; however, when and in whom testosterone should be replaced remain unanswered questions. OBJECTIVE: The aim of our study was to define the prevalence of androgen deficiency in this patient group through assessment of testosterone levels and related measures. DESIGN: This was a cross-sectional, observational study of cases and controls. We recruited 176 cancer survivors and 213 controls, aged 25-45 yr. RESULTS: Of cancer survivors, 97% had received chemotherapy and 40% radiotherapy. Cancer survivors had lower total testosterone (tT) levels than controls (mean difference 2.67 nmol/liter; 95% confidence interval 1.58-3.76; P = 0.003), and 24 of 176 (13.6%; 95% confidence interval 9.3-19.5) had a tT less than 10 nmol/liter, which was less than 2.5% centile for controls. Cancer survivors had a greater fat mass, higher fasting insulin and glucose levels, increased fatigue, and reduced sexual function and health-related quality of life. In both cohorts, the tT correlated negatively with insulin levels and negatively with body fat mass; however, the difference in tT between them was independent of fat mass. We measured tT and SHBG and calculated bioavailable testosterone. The changes in calculated bioavailable testosterone were similar to tT. CONCLUSIONS: A significant proportion of young male cancer survivors had a frankly low tT associated with an increased fat mass and insulin level compared with controls. These factors would be predicted to improve in response to testosterone replacement therapy and provide a powerful argument for an interventional study of testosterone therapy in young male cancer survivors.

Amyloid beta1-40 quantification in CSF: comparison between chromatographic and immunochemical methods.

BACKGROUND/AIMS: Amyloid beta (Abeta) is the principal component of senile plaques, one of the hallmarks of Alzheimer's disease (AD). Evidence is accumulating that soluble aggregates (oligomers) of Abeta are important in the pathogenesis of AD. METHODS: We compared three different methods for quantification of the 40 amino acid form of Abeta (Abeta40) in CSF, two based on antibodies [ELISA and surface-enhanced laser desorption/ionization-time of flight (SELDI-TOF) with antibody-coated arrays] and one based on direct binding of proteins to a protein array [SELDI-TOF and immobilized metal affinity [copper] (IMAC30)]. RESULTS: CSF Abeta40 concentration was only found to be significantly elevated in AD (127% of control levels; p=0.0095) using SELDI-TOF with IMAC30 arrays. CONCLUSIONS: These data suggest that the measured Abeta level in CSF may differ depending on whether antibody-based methods are used or not, possibly caused by epitope masking due to Abeta oligomerization or to binding of Abeta to carrier proteins.

The effects of growth hormone treatment on health-related quality of life in children.

BACKGROUND/AIMS: The effects of growth hormone deficiency (GHD) on linear growth in children are well documented, but there is less convincing evidence regarding the impact on health-related quality of life (QOL). We examined QOL in children aged 8-16 years with acquired GHD following treatment for malignancy (AGHD) or idiopathic GHD (IGHD) on commencing growth hormone treatment (GHT) over 6 months. We adopted a longitudinal design involving consecutive patients and their families attending clinic over an 18-month period. Mothers and children were invited to complete questionnaires before GHT (T1) and 6 months later (T2). METHODS: Mothers of 22 children (AGHD n = 14; IGHD n = 8) completed standardized measures of child QOL and behaviour. Children completed parallel measures of QOL, short-term memory tasks and fitness either in clinic or at the family home. RESULTS: For children with AGHD, QOL was significantly below population norms at T1 and improved over time. For children diagnosed with IGHD, QOL at T1 was below, but comparable with population norms. QOL improved over time, though not significantly. CONCLUSION: GHT is potentially valuable for improving QOL in children, especially in cases of AGHD. We conclude that benefits of GHT for QOL need to be evaluated independent of different diagnostic groups.

Chronic restraint stress induces changes in synapse morphology in stratum lacunosum-moleculare CA1 rat hippocampus: a stereological and three-dimensional ultrastructural study.

Chronic restraint stress is known to affect the morphology and synaptic organization of the hippocampus, predominantly within CA3 but also in CA1 and dentate gyrus. In this study, we provide the first evidence for specific ultrastructural alterations affecting asymmetric axo-spinous synapses in CA1 stratum lacunosum-moleculare following chronic restraint stress (6 h/day, 21 days) in the rat. The structure of asymmetric axo-spinous post-synaptic densities was investigated using serial section three-dimensional reconstruction procedures in control (n=4) and chronic restraint stress (n=3) animals. Dendritic spine profiles (spine head+neck) associated with the sampled synaptic contacts (30 per animal) were also reconstructed in three-dimensions. Morphometric analyses revealed a significant increase in post-synaptic density surface area (+36%; P=0.03) and a highly significant increase in post-synaptic density volume (+79%; P=0.003) in the chronic restraint stress group. These changes were directly associated with 'non-macular' (perforated, complex and segmented) post-synaptic densities. A highly significant overall increase in the 'post-synaptic density surface area/spine surface area' ratio was also detected in the chronic restraint stress group (+27%; P=0.002). In contrast, no quantitative changes in spine parameters were found between groups. The Cavalieri method was used to assess the effects of chronic restraint stress exposure upon CA1 hippocampal volume. The mean volume of total dorsal anterior CA1 hippocampus was significantly lower in the chronic restraint stress group (-16%; P=0.036). However, when corrected for volume changes, no significant alteration in a relative estimate of the mean number of asymmetric axo-spinous synapses was detected in CA1 stratum lacunosum-moleculare between control and chronic restraint stress groups. The data indicate a structural remodeling of excitatory axo-spinous synaptic connectivity in rat CA1 stratum lacunosum-moleculare as a result of chronic restraint stress.

Passive avoidance training decreases synapse density in the hippocampus of the domestic chick.

The bird hippocampus (Hp), although lacking the cellular lamination of the mammalian Hp, possesses comparable roles in spatial orientation and is implicated in passive avoidance learning. As in rodents it can be divided into dorsal and ventral regions based on immunocytochemical, tracing and electrophysiological studies. To study the effects of passive avoidance learning on synapse morphometry in the Hp, spine and shaft synapse densities of 1-day-old domestic chicks were determined in dorsal and ventral Hp of each hemisphere by electron microscopy, 6 and 24 h following training to avoid pecking at a bead coated with a bitter-tasting substance, methyl anthranilate (MeA). The density of asymmetric spine and shaft synapses in MeA-trained birds at 6 h post-training was significantly lower in the dorsal and ventral Hp of the right hemisphere relative to control (untrained) chicks, but by 24 h this difference was absent. A hemispheric asymmetry was apparent in the ventral Hp where the water-trained group showed enhanced shaft and spine synapse density in the left hemisphere, whilst in the MeA-trained group only asymmetric shaft synapses follow the same pattern in relation to the right hemisphere. There were no differences in asymmetric shaft synapses in the dorsal Hp at 6 h post-training, but at 24 h post-training there was a reduction in the density of shaft synapses in the right hemisphere in MeA compared with control birds. These data are discussed in relation to the pruning effects of stress and learning on synapse density in chick Hp.

Teaching and learning consultation skills for paediatric practice.

Effective consultations with patients and their families are important for patient satisfaction, adherence to treatment, and recovery from illness. Communication problems among health professionals are common. Fortunately, the skills of effective communication can be taught and learned. This paper highlights evidence based approaches to teaching these skills with minimal resources.

High incidence of late effects found in Hodgkin's lymphoma survivors, following recall for breast cancer screening.

Assessment of late effects in a cohort of female Hodgkin's lymphoma patients treated with mantle radiotherapy, identified from the DoH breast cancer screening recall showed high mortality and frequent undiagnosed abnormalities in tissues affected by radiotherapy. With increasing age, this patient group may suffer premature cardiac and respiratory morbidity.

Chemically induced long-term potentiation increases the number of perforated and complex postsynaptic densities but does not alter dendritic spine volume in CA1 of adult mouse hippocampal slices.

Examination of the morphological correlates of long-term potentiation (LTP) in the hippocampus requires the analysis of both the presynaptic and postsynaptic elements. However, ultrastructural measurements of synapses and dendritic spines following LTP induced via tetanic stimulation presents the difficulty that not all synapses examined are necessarily activated. To overcome this limitation, and to ensure that a very large proportion of the synapses and spines examined have been potentiated, we induced LTP in acute hippocampal slices of adult mice by addition of tetraethylammonium (TEA) to a modified CSF containing an elevated concentration of Ca(2+) and no Mg(+). Quantitative electron microscope morphometric analyses and three-dimensional (3-D) reconstructions of both dendritic spines and postsynaptic densities (PSDs) in CA1 stratum radiatum were made on serial ultrathin sections. One hour after chemical LTP induction the proportion of macular (unperforated) synapses decreased (50%) whilst the number of synapses with simple perforated and complex PSDs (nonmacular) increased significantly (17%), without significant changes in volume and surface area of the PSD. In addition, the surface area of mushroom spines increased significantly (13%) whilst there were no volume differences in either mushroom or thin spines, or in surface area of thin spines. CA1 stratum radiatum contained multiple-synapse en passant axons as well as multiple-synapse spines, which were unaffected by chemical LTP. Our results suggest that chemical LTP induces active dendritic spine remodelling and correlates with a change in the weight and strength of synaptic transmission as shown by the increase in the proportion of nonmacular synapses.