Assessing the benefits and usefulness of Schwartz Centre rounds in second-year medical students using clinical educator-facilitated group work session: not just "a facilitated moan"!

BACKGROUND

An experiential curriculum exposing medical students to the clinic early has many benefits but comes with the emotional stress this environment engenders. Schwartz rounds (SR) are an effective means to combat emotional stress and increasingly used in UK and USA hospitals. Recent studies show that the SR format may also provide benefits for medical students. This study aimed to investigate whether the guidance of SR in second year medical students provides the same benefits as to healthcare professionals.

METHODS

SR assessment involved 83 s year MBChB students in facilitated groupwork sessions. Topics discussed were "change and resilience" and "duty of candour". Students completed a Likert Scale questionnaire evaluating outcomes proffered by the Point of Care Foundation in collaboration with the Schwartz Foundation, with freeform feedback.

RESULTS

There was an 86% completion rate with 25% providing written feedback. Participants were more likely to agree than disagree that SR were beneficial. SR effectiveness in enhancing students' working relationship awareness and skills was strongly correlated with understanding the purpose of, and engagement with, the SR (P < 0.001). Similarly, engagement with the SR was strongly correlated with self-reporting of enhanced patient-centredness (P < 0.001). Freeform feedback could be grouped into five themes that revolved around understanding of the SR and engagement with the process. Many positive comments regarded the SR as a forum not only to "learn experientially" but to so in a "safe environment". Many negative comments stemmed from students not seeing any benefits of engagement with the SR, in that sharing experiences was "unbeneficial", "empathy is inherent and not learnt", or that sharing emotional problems is simply "moaning".

CONCLUSION

SRs are an effective way of fostering empathy and understanding towards patients and colleagues. However, for the students to benefit fully from the SR it is necessary for them to engage and understand the process. Therefore, for the successful implementation of SR into pre-clinical medical education, it is important to help students realise that SR are not merely a "facilitated whinge".

An Unexpected Cause of an Acute Hypersensitivity Reaction during Recovery from Anaesthesia

Acute hypersensitivity reactions to chlorhexidine in the operating room are probably more likely to occur during the early phases of anaesthesia because chlorhexidine is often used for cleaning the surgical field or during placement of indwelling catheters. We report a case of an acute hypersensitivity reaction that occurred in the post anaesthetic care unit. Subsequent skin testing suggested sensitivity to chlorhexidine, which had been applied over the vaginal mucosa at the end of surgery. Relevant issues in the investigation of acute hypersensitivity reactions in the post anaesthetic period are discussed.

Unrecognized Benign Paroxysmal Positional Vertigo in Elderly Patients

Balance disorders in elderly patients are associated with an increased risk of falls but are often difficult to diagnose because of comorbid chronic medical problems. We performed a cross-sectional study to determine the prevalence of unrecognized benign paroxysmal positional vertigo (BPPV) and associated lifestyle sequelae in a public, inner-city geriatric population. Dizziness was found in 61% of patients, whereas balance disorders were found in 77% of patients. Nine percent were found to have unrecognized BPPV. Multivariate analysis demonstrated that the presence of a spinning sensation and the absence of a lightheadedness sensation predicted the presence of unrecognized BPPV. Patients with unrecognized BPPV were more likely to have reduced activities of daily living scores, to have sustained a fall in the previous 3 months, and to have depression. These data indicate that unrecognized BPPV is common within the elderly population and has associated morbidity. Further prospective studies are warranted.

Hippocampal circuit dysfunction in the Tc1 mouse model of Down syndrome

Hippocampal pathology is likely to contribute to cognitive disability in Down syndrome, yet the neural network basis of this pathology and its contributions to different facets of cognitive impairment remain unclear. Here we report dysfunctional connectivity between dentate gyrus and CA3 networks in the transchromosomic Tc1 mouse model of Down syndrome, demonstrating that ultrastructural abnormalities and impaired short-term plasticity at dentate gyrus-CA3 excitatory synapses culminate in impaired coding of new spatial information in CA3 and CA1 and disrupted behavior in vivo. These results highlight the vulnerability of dentate gyrus-CA3 networks to aberrant human chromosome 21 gene expression and delineate hippocampal circuit abnormalities likely to contribute to distinct cognitive phenotypes in Down syndrome.

On the Autistic Spectrum Disorder concordance rates of twins and non-twin siblings

Using the Interactive Autism Network Research Database, the Autistic Spectrum Disorder concordance rates for twins and non-twin siblings were calculated. For males, females and both genders together, the concordance rate for dizygotic twins is approximately twice that of non-twin siblings. We also determined that the concordance rate for non-twin siblings decreases as the interval between pregnancies increases. Our results appear to indicate that the uterine environment may contribute to autism concordance rates.

Visual deprivation alters dendritic bundle architecture in layer 4 of rat visual cortex

The effect of visual deprivation followed by light exposure on the tangential organisation of dendritic bundles passing through layer 4 of the rat visual cortex was studied quantitatively in the light microscope. Four groups of animals were investigated: (I) rats reared in an environment illuminated normally--group 52 dL; (II) rats reared in the dark until 21 days postnatum (DPN) and subsequently light exposed for 31 days-group 21/31; (III) rats dark reared until 52 DPN and then subsequently light exposed for 3 days--group 3 dL; and (IV) rats totally dark reared until 52 DPN--group 52 DPN. Each group contained five animals. Semithin 0.5-1-μm thick resin-embedded sections were collected from tangential sampling levels through the middle of layer 4 in area 17 and stained with Toluidine Blue. These sections were used to quantitatively analyse the composition and distribution of dendritic clusters in the tangential plane. The key result of this study indicates a significant reduction in the mean number of medium- and small-sized dendritic profiles (diameter less than 2 μm) contributing to clusters in layer 4 of groups 3 dL and 52 dD compared with group 21/31. No differences were detected in the mean number of large-sized dendritic profiles composing a bundle in these experimental groups. Moreover, the mean number of clusters and their tangential distribution in layer 4 did not vary significantly between all four groups. Finally, the clustering parameters were not significantly different between groups 21/31 and the normally reared group 52 dL. This study demonstrates, for the first time, that extended periods of dark rearing followed by light exposure can alter the morphological composition of dendritic bundles in thalamorecipient layer 4 of rat visual cortex. Because these changes occur in the primary region of thalamocortical input, they may underlie specific alterations in the processing of visual information both cortically and subcortically during periods of dark rearing and light exposure.

Cross-cultural adaptation and validation of a quality of life questionnaire: the Nasal Obstruction Symptom Evaluation questionnaire

BACKGROUND

The Nasal Obstruction Symptom Evaluation (NOSE) instrument is a disease-specific questionnaire for assessing the outcome of an intervention in nasal obstruction in trials. This instrument is only available in the English language and cross-culturally valid questionnaires are very important for all research, including nasal obstruction. The aim of the current study was to reproduce the cross-cultural adaptation process for the NOSE questionnaire in the Portuguese language (NOSE-p).

METHODOLOGY/PRINCIPAL

Cross-cultural adaptation and validation of the instrument were divided into two stages. Stage 1 involved four bilingual professionals, an expert committee and the author of the original instrument. In Stage 2, the NOSE-p was tested on 33 patients undergoing septoplasty for internal consistency, test-retest reliability, construct validity, discriminant validity, criterion validity, and response sensitivity.

RESULTS

The cross-cultural adaptation process was completed and the NOSE-p was demonstrated to be a valid instrument with satisfactory construct validity. It showed an adequate internal consistency reliability and adequate test-retest reliability. It could discriminate between patients with and without nasal obstruction and it has a high response sensitivity to change.

CONCLUSIONS

The cross-cultural adaptation and validation process demonstrated to be valid and the NOSE-p proved to be applicable in Brazil.

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.

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.

Frequency of sinus disease in normal subjects and patients with benign paroxysmal positional vertigo

BACKGROUND/AIMS

To determine if patients with benign paroxysmal positional vertigo (BPPV) have a higher frequency of rhinosinusitis than people with normal vestibular function.

METHODS

The subjects were 52 patients with BPPV and 46 normal people. Every subject had a sinus CT scan, a blood draw for IgE and a rhinologic examination by an otolaryngologist.

RESULTS

The frequency of rhinosinusitis based on physician diagnosis was 49% and based on CT scan findings 59%. This difference approached significance (p = 0.08). The observed frequency of rhinosinusitis was higher than predicted by survey data about the southern US region. The data trended toward higher prevalence of rhinosinusitis (by physician diagnosis) in the BPPV patients versus controls (58 vs. 39%, p = 0.06).

CONCLUSION

BPPV patients have a higher frequency of sinus disease compared to people with normal vestibular systems, perhaps due to age differences, but physiologic factors may also be involved. The higher frequency of rhinosinusitis in this geographical area than reported rates based on survey data raises concerns about the usefulness of questionnaire data for estimating population prevalence.

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.

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.

Identification and management of undiagnosed and undertreated allergic rhinitis in adults and children

Allergic rhinitis (AR) is a common health problem that affects adults, adolescents and children and is often undiagnosed or inadequately treated. Because AR is not a life-threatening disease, many patients do not seek medical treatment for their symptoms, and others self-medicate with over-the-counter medications, often sedating antihistamines. However, untreated or inadequately treated AR can substantially impair overall quality of life (QOL) by causing fatigue, headache, cognitive impairment and other problems. The risk for comorbid conditions, such as asthma, otitis media, and lymphoid hypertrophy with obstructive sleep apnea, can increase, and the symptoms of AR can worsen if AR is not adequately treated. Among the symptoms of AR, nasal congestion has been described by patients as the most bothersome because it disrupts sleep, resulting in diminished daytime performance. A new congestion screening tool, the Congestion Quantifier, has been developed to aid in the diagnosis and treatment of AR and to help guide treatment decisions. Intranasal corticosteroids (INSs) are recommended as effective pharmaceutical treatments for controlling the symptoms of AR. Randomized, controlled trials in children and adults have demonstrated that INSs relieve rhinitis symptoms, thereby improving QOL in individuals with seasonal or perennial AR. Most INSs are approved for use in children >or=6 years of age, but mometasone furoate and fluticasone furoate are approved for use in children as young as 2 years of age and fluticasone propionate for children >or=4 years old. Long-term benefits have also been seen with the use of immunotherapy, although some patients, especially children, resist the injections used in subcutaneous immunotherapy. Recent studies with sublingual immunotherapy have indicated that it might be an effective and well-tolerated alternative to immunotherapy injections.

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.

Reversible reduction in dendritic spines in CA1 of rat and ground squirrel subjected to hypothermia-normothermia in vivo: A three-dimensional electron microscope study

A study was made at electron microscope level of changes in the three-dimensional (3-D) morphology of dendritic spines and postsynaptic densities (PSDs) in CA1 of the hippocampus in ground squirrels, taken either at low temperature during hibernation (brain temperature 2-4 degrees C), or after warming and recovery to the normothermic state (34 degrees C). In addition, the morphology of PSDs and spines was measured in a non-hibernating mammal, rat, subjected to cooling at 2 degrees C at which time core rectal temperature was 15 degrees C, and then after warming to normothermic conditions. Significant differences were found in the proportion of thin and stubby spines, and shaft synapses in CA1 for rats and ground squirrels for normothermia compared with cooling or hibernation. Hypothermia induced a decrease in the proportion of thin spines, and an increase in stubby and shaft spines, but no change in the proportion of mushroom spines. The changes in redistribution of these three categories of spines in ground squirrel are more prominent than in rat. There were no significant differences in synapse density determined for ground squirrels or rats at normal compared with low temperature. Measurement of spine and PSD volume (for mushroom and thin spines) also showed no significant differences between the two functional states in either rats or ground squirrels, nor were there any differences in distances between neighboring synapses. Spinules on dendritic shafts were notable qualitatively during hibernation, but absent in normothermia. These data show that hypothermia results in morphological changes which are essentially similar in both a hibernating and a non-hibernating animal.

Passive avoidance training is correlated with decreased cell proliferation in the chick hippocampus

One-trial passive avoidance learning (PAL), where the aversive stimulus is the bitter-tasting substance methylanthranilate (MeA), affects neuronal and synaptic plasticity in learning-related areas of day-old domestic chicks (Gallus domesticus). Here, cell proliferation was examined in the chick forebrain by using 5-bromo-2-deoxyuridine (BrdU) at 24 h and 9 days after PAL. At 24 h post-BrdU injection, there was a significant reduction in labelling in MeA-trained chicks in both the dorsal hippocampus and area parahippocampalis, in comparison to controls. Moreover, double-immunofluorescence labelling for BrdU and the nuclear neuronal marker (NeuN) showed a reduction of neuronal cells in the dorsal hippocampus of the MeA-trained group compared with controls (35 and 49%, respectively). There was no difference in BrdU labelling in hippocampal regions between trained and control groups of chicks at 9 days post-BrdU injection; however, the number of BrdU-labelled cells was considerably lower than at 24 h post-BrdU injection, possibly due to migration of cells within the telencephalon rather than cell loss as apoptotic analyses at 24 h and 9 days post-BrdU injection did not demonstrate differences in cell death between treatment groups. Cortisol levels increased in the chick hippocampus of MeA-trained birds 20 min after PAL, suggesting the possibility of a stress-related mechanism of cell proliferation reduction in the hippocampus. In contrast to hippocampal areas, the olfactory bulb, an area strongly stimulated by the strong-smelling MeA, showed increased cell genesis in comparison to controls at both 24 h and 9 days post-training.

On a possible early identification procedure for babies at high risk for autistic spectrum disorder

A hypothesis for a method that may make possible the early identification of neonates at high risk for later development of autistic spectrum disorder (ASD) is set forth. The method is a test of the assertion that unusually high testosterone concentrations in amniotic fluid (TECAFs) are predictive of later ASD diagnoses. The statistical distribution of TECAFS, obtained in the 14-20th week of pregnancy, is used to determine the critical TECAF value above which the highest 2% lie and thus identify the babies at high risk for later ASD syndromes. From presently available data a single numerical value cannot be obtained. However, a critical value calculated from the mean TECAF value of a group of gender identified amniotic fluid samples, which are all assayed by the same technique, and multiples of the standard deviation (SD) of the TECAFs of that group, leads to an estimate of the critical TECAF value. We estimate that this critical value is equal to the mean plus 2.6 times the standard deviation, (m+2.6 SD), of the set of measurements. A rough calculation of the number of neonates that would be needed for a test of this method is discussed.

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.

Subunit Dependencies ofN-Methyl-d-aspartate (NMDA) Receptor-Induced α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptor Internalization

N-Methyl-D-aspartate (NMDA) receptor (NMDAR) activity regulates the net number of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors (AMPAR) at the cell surface by modulating the balance between AMPAR membrane insertion and endocytosis. In this study, we addressed the role of NMDAR subtypes and of NMDAR-mediated Ca2+ influx in the NMDAR-induced endocytosis of GluR2-containing AMPARs in primary murine hippocampal neurons. We found that NMDAR activation enhanced the endocytosis of AMPARs containing the GluR2 splice variants with short, but not long, cytoplasmic tails. NMDA-induced GluR2 endocytosis was completely inhibited by pharmacological block of NR2B-containing NMDARs. In turn, preferential block of NR2A-containing NMDARs did not affect NMDA-induced AMPAR endocytosis, indicating that AMPAR internalization is controlled by a restricted set of NMDARs. The NMDA-induced GluR2 internalization was also observed in the absence of extracellular Na+ ions, suggesting that membrane depolarization is not a prerequisite for this effect. Furthermore, the activation of Ca2+-impermeable NMDARs containing the mutant NR1(N598R) subunit failed to enhance AMPAR endocytosis, indicating a requirement of Ca2+ influx directly through the NMDAR channels. In summary, our findings suggest that the NMDAR-induced selective internalization of short C-terminal GluR2-containing AMPARs requires a Ca2+ signal that originates from NMDAR channels and is processed in an NMDAR subtype-restricted manner.

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.

Three-dimensional reconstruction of synapses and dendritic spines in the rat and ground squirrel hippocampus: new structural-functional paradigms for synaptic function

Published data are reviewed along with our own data on synaptic plasticity and rearrangements of synaptic organelles in the central nervous system. Contemporary laser scanning and confocal microscopy techniques are discussed, along with the use of serial ultrathin sections for in vivo and in vitro studies of dendritic spines, including those addressing relationships between morphological changes and the efficiency of synaptic transmission, especially in conditions of the long-term potentiation model. Different categories of dendritic spines and postsynaptic densities are analyzed, as are the roles of filopodia in originating spines. The role of serial ultrathin sections for unbiased quantitative stereological analysis and three-dimensional reconstruction is assessed. The authors' data on the formation of more than two synapses on single mushroom spines on neurons in hippocampal field CA1 are discussed. Analysis of these data provides evidence for new paradigms in both the organization and functioning of synapses.

Long-term potentiation in the rat dentate gyrus is associated with enhanced Arc/Arg3.1 protein expression in spines, dendrites and glia

Electron microscopic immunocytochemical methods were used to determine the localization, subcellular distribution and expression of activity-regulated cytoskeletal protein (Arc/Arg3.1) in dentate gyrus after unilateral induction of long-term potentiation (LTP) in the perforant pathway of anaesthetized rats. At 2 h post-induction, immunoreaction product was visible in the dentate gyrus in both the granule cell and molecular layers. Arc expression was higher in the potentiated than the unstimulated contralateral hemisphere. Single-section electron microscopy analysis in unstimulated tissue and in tissue prepared 2 and 4 h after LTP induction showed Arc immunoreactivity (Arc-IR) in dendrites, dendritic spines and glia. Arc-IR was associated with synaptic and non-synaptic plasma membrane apposed to axon terminals and with cytoplasmic organelles, including the cytoskeleton. Arc-IR was also present in neuronal perikarya and there was occasional labelling of nuclei and axons. At 2 h post-LTP induction, there were significant increases in Arc-IR within the granule cell and molecular layers of the dentate gyrus and particularly within the middle molecular layer relative to the inner and outer molecular layers. This increase in Arc expression 2 h after LTP induction was blocked by the N-methyl-D-aspartate receptor antagonist (RS)-3-2-carboxypiperazin-4-yl-propyl-1-phosphonic acid. In animals killed 4 h after LTP induction, Arc expression had declined and differences between the potentiated and unpotentiated hemispheres were no longer significant. Our data provide ultrastructural evidence for a transient LTP-associated increase in the expression of Arc protein in the middle molecular layer of the dentate gyrus, with preferential targeting to dendrites, dendritic spines and glia.

Stress suppresses and learning induces plasticity in CA3 of rat hippocampus: a three-dimensional ultrastructural study of thorny excrescences and their postsynaptic densities

Chronic stress and spatial training have been proposed to affect hippocampal structure and function in opposite ways. Previous morphological studies that addressed structural changes after chronic restraint stress and spatial training were based on two-dimensional morphometry which does not allow a complete morphometric characterisation of synaptic features. Here, for the first time in such studies, we examined these issues by using three-dimensional (3-D) reconstructions of electron microscope images taken from thorny excrescences of hippocampal CA3 pyramidal cells. Ultrastructural alterations in postsynaptic densities (PSDs) of thorny excrescences receiving input from mossy fibre boutons were also determined, as were changes in numbers of multivesicular bodies (endosome-like structures) within thorny excrescences and dendrites. Quantitative 3-D data demonstrated retraction of thorny excrescences after chronic restraint stress which was reversed after water maze training, whilst water maze training alone increased thorny excrescence volume and number of thorns per thorny excrescence. PSD surface area was unaffected by restraint stress but water maze training increased both number and area of PSDs per thorny excrescence. In restrained rats that were water maze trained PSD volume and surface area increased significantly. The proportion of perforated PSDs almost doubled after water maze training and restraint stress. Numbers of endosome-like structures in thorny excrescences decreased after restraint stress and increased after water maze training. These findings demonstrate that circuits involving contacts between mossy fibre terminals and CA3 pyramidal cells at stratum lucidum level are affected conversely by water maze training and chronic stress, confirming the remarkable plasticity of CA3 dendrites. They provide a clear illustration of the structural modifications that occur after life experiences noted for their different impact on hippocampal function.

Pregnenolone sulfate enhances neurogenesis and PSA-NCAM in young and aged hippocampus

Age-dependent cognitive impairments have been correlated with functional and structural modifications in the hippocampal formation. In particular, the brain endogenous steroid pregnenolone-sulfate (Preg-S) is a cognitive enhancer whose hippocampal levels have been linked physiologically to cognitive performance in senescent animals. However, the mechanism of its actions remains unknown. Because neurogenesis is sensitive to hormonal influences, we examined the effect of Preg-S on neurogenesis, a novel form of plasticity, in young and old rats. We demonstrate that in vivo infusion of Preg-S stimulates neurogenesis and the expression of the polysialylated forms of NCAM, PSA-NCAM, in the dentate gyrus of 3- and 20-month-old rats. These influences on hippocampal plasticity are mediated by the modulation of the gamma-aminobutyric acid receptor complex A (GABA(A)) receptors present on hippocampal neuroblasts. In vitro, Preg-S stimulates the division of adult-derived spheres suggesting a direct influence on progenitors. These data provide evidence that neurosteroids represent one of the local secreted signals controlling hippocampal neurogenesis. Thus, therapies which stimulate neurosteroidogenesis could preserve hippocampal plasticity and prevent the appearance of age-related cognitive disturbances.

Chronic restraint stress down-regulates amygdaloid expression of polysialylated neural cell adhesion molecule

The amygdala is a brain area which plays a decisive role in fear and anxiety. Since exposure to chronic stress can induce profound effects in emotion and cognition, plasticity in specific amygdaloid nuclei in response to prior stress has been hypothesized to account for stress-induced emotional alterations. In order to identify amygdala nuclei which may be affected under chronic stress conditions we evaluated the effects of 21-days chronic restraint stress on the expression of a molecule implicated crucially in alterations in structural plasticity: the polysialylated neural cell adhesion molecule. We found that polysialylated neural cell adhesion molecule-immunoreactivity within the amygdala, present in somata and neuronal processes, has a regional gradient with the central medial and medial amygdaloid nuclei showing the highest levels. Our results demonstrate that chronic restraint stress induced an overall reduction in polysialylated neural cell adhesion molecule-immunoreactivity in the amygdaloid complex, mainly due to a significant decrease in the central medial amygdaloid and medial amygdaloid nuclei. Our data suggest that polysialylated neural cell adhesion molecule in these nuclei may play a prominent role in functional and structural remodeling induced by stress, being a potential mechanism for cognitive and emotional modulation. Furthermore, these finding provide the first clear evidence that life experiences can regulate the expression of polysialylated neural cell adhesion molecule in the amygdaloid complex.

[Three-dimensional reconstruction of synapse and dendritic spines in the hippocampus of rats and ground squirrels: new paradigms of the structure and function of a synapse]

The article reviews the literature data and results obtained by the authors concerning synaptic plasticity and remodeling of synaptic organelles in the central nervous system. Modern techniques of laser scanning confocal microscopy and serial thin sectioning for in vivo and in vitro studies of dendritic spines including a correlation between morphological changes and synaptic transmission efficiency are discussed, particularly, in relation to long-term potentiation. Organization of different types of dendritic spines and involvement of filopodia in spine genesis are examined. Significance of serial ultrathin sections for unbiased quantitative stereological analysis and three-dimensional reconstructions is discussed. The contact of one dendritic spine with two presynaptic boutons (multiple synapses) on both CA1 mushroom dendritic spines is discussed. The analyzed findings suggest new ideas for organization and functioning of synapses.

Remodelling of synaptic morphology but unchanged synaptic density during late phase long-term potentiation(ltp): A serial section electron micrograph study in the dentate gyrus in the anaesthetised rat

In anaesthetised rats, long-term potentiation (LTP) was induced unilaterally in the dentate gyrus by tetanic stimulation of the perforant path. Animals were killed 6 h after LTP induction and dendritic spines and synapses in tetanised and untetanised (contralateral) hippocampal tissue from the middle molecular layer (MML) were examined in the electron microscope using stereological analysis. Three-dimensional reconstructions were also used for the first time in LTP studies in vivo, with up to 130 ultrathin serial sections analysed per MML dendritic segment. A volume sampling procedure revealed no significant changes in hippocampal volume after LTP and an unbiased counting method demonstrated no significant changes in synapse density in potentiated compared with control tissue. In the potentiated hemisphere, there were changes in the proportion of different spine types and their synaptic contacts. We found an increase in the percentage of synapses on thin dendritic spines, a decrease in synapses on both stubby spines and dendritic shafts, but no change in the proportion of synapses on mushroom spines. Analysis of three-dimensional reconstructions of thin and mushroom spines following LTP induction revealed a significant increase in their volume and area. We also found an increase in volume and area of unperforated (macular) and perforated (segmented) postsynaptic densities. Our data demonstrate that whilst there is no change in synapse density 6 h after the induction of LTP in vivo, there is a considerable restructuring of pre-existing synapses, with shaft and stubby spines transforming to thin dendritic spines, and mushroom spines changing only in shape and volume.

Ultrastructural and behavioural changes precede amyloid deposition in a transgenic model of Alzheimer’s disease

We describe the thorough characterisation of a new transgenic mouse line overexpressing the 695-amino acid isoform of human amyloid precursor protein harbouring the Swedish double familial Alzheimer's disease mutation. This line, referred to as TAS10, exhibits neuropathological features and cognitive deficits that are closely correlated to the accumulation of Abeta in their brain and that are reminiscent of those observed in AD. Data on the TAS10 line are presented at five time points: 2, 6, 12, 18 and 24 months in a longitudinal study. The TAS10 line is characterised by the following changes: i) significant age-related increases in the levels of total and individual species (1-40, 1-42) of beta-amyloid in the brains of transgenics compared with non-transgenic littermates; ii) transgenic mice showed pronounced spatial learning deficits in the Morris water maze at 6 months and working memory deficits by 12 months; iii) amyloid plaque and associated pathologies were observed by the 12-month time point and the burden increased substantially, particularly in the cortex, by 18 months; iv) electron microscopy of the hippocampus of transgenic mice showed evidence of abnormal ultrastructural features such as dystrophic neurites and lipid deposits that developed from 6 months and increased in number and severity with age. Morphometric studies demonstrate that the synapse to neuron ratio is higher in transgenics than in control mice at 12 months, but this ratio decreases as they age and synapse size increases. Thus, this mouse model exhibits a close correlation of amyloid burden with behavioural deficits and ultrastructural abnormalities and so represents an ideal system to study the mechanisms underlying the impact of amyloid pathology on CNS function.

Synaptophysin immunogold labelling of synapses decreases in dentate gyrus of the hippocampus of aged rats

Synaptophysin expression was assessed in dentate gyrus prepared from aged (22 months) and young (4 months) rats by immunoblotting and post-embedding immunolabelling at electron microscope level. Immunoblotting showed qualitatively that there was a marked reduction in synaptophysin expression in synaptosomes of aged compared with young rats. Immunogold labelling studies in the medial molecular layer of the dentate gyrus demonstrated that gold particles were restricted to pre-synaptic boutons, and were present mainly on the membranes of the synaptic vesicles or occasionally inside vesicles. In aged rats, immunolabelling patterns and the density of immunogold particles per pre-synaptic bouton were almost 50% lower than in younger rats. However, because boutons were larger in older rats the actual labelling density per unit area of bouton (3.77) was even lower than in the young rats (7.74). The role of synaptophysin in neural plasticity and ageing should be further examined.

[Three-dimentional organization of synapses and astroglia in the hippocampus of rats and ground squirrels: new structural and functional paradigms of the synapse function]

The literature data and our own data on the synaptic plasticity and remodeling of synaptic organelles in the central nervous system are reviewed. Modern techniques of laser scanning confocal microscopy and serial thin sectioning for in vivo and in vitro studies of dendritic spines, including the relationship between morphological changes and the efficacy of synaptic transmission, are discussed using, in particular, a model of long-term potentiation. The organization of dendritic spines and postsynaptic densities of different categories as well as the role of filopodia in spine genesis were analyzed. It was shown that the method of serial ultrathin sections is the most effective for unbiased quantitative stereological analysis and 3D reconstructions. By using the refined method of serial ultrathin sections with subsequent three-dimensional reconstructions, the presence of giant mitochondria in hippocampal neuronal dendrites was demonstrated. It was shown that smooth endoplasmic reticulum forms a unified continuum with the outer membrane of the mitochondrial envelope within dendrites. It was suggested that this continuum provides calcium tunneling, which makes possible intracellular signal transduction during synaptic transmission. Evidence is presented indicating the presence of gap junctions ("electrical synapses") in the synapses of mammalian brain, as well as between glial processes, and between glial cells and neurons. Our data and the data of other authors show that glial cell processes form a structural and functional glial network, which modulates the functioning of the neuronal network. The connection of dendritic spines with the glial network is shown on 3D reconstructions by analyzing the neuropil volume in CA1 hippocampal area of ground squirrels in three functional states: normothermia, provoked arousal, and hibernation when brain temperature falls below 6 degrees C. The own data of the authors are discussed indicating the formation of more than five presynaptic boutons (multiple synapses) on both CA1 mushroom-like dendritic spines and CA3 thorny excrescences. On the basis of the analysis, new ideas of the organization and functioning of synapses were suggested.

Passive avoidance training enhances cell proliferation in 1-day-old chicks

One-day-old domestic chicks were injected i.p. with bromodeoxyuridine (BrdU) before training on a one-trial passive avoidance task where the aversive experience was a bead coated with a bitter tasting substance, methyl anthranilate (MeA). Animals were tested 24 h later; those avoiding (if MeA-trained) or pecking if water (W)-trained (which they peck appetitively), along with a group of untrained naïve chicks, were used to determine cell proliferation either 24 h or 9 days post BrdU injection. In all three groups, BrdU positive cells were identified sparsely throughout the forebrain but labelling was pronounced around ventricular zone (VZ) surfaces at both 24 h and 9 days post-BrdU-injection. Double immunolabelling with neuronal specific antibodies, to either NeuN, or beta-tubulin III, confirmed that most BrdU labelled cells appeared to be neurons. Unbiased stereological analysis of labelled cells in selected forebrain areas 24 h post BrdU injection showed a significant MeA-training induced increase in labelled cells in both the dorsal VZ surface bordering the intermediate and medial hyperstriatum ventrale (IMHV) and the tuberculum olfactorium (TO). By 9 days post-BrdU-injection, there was a significantly greater number of BrdU labelled cells in MeA-trained birds within the IMHV, lobus parolfactorius (LPO) and TO. These results demonstrate that avoidance training in 1-day-old chicks has a marked effect on cell proliferation, in the LPO and IMHV, regions of the chick previously identified as a key loci of memory formation, and in a second region (TO), which has olfactory functions, but has not been previously investigated in relation to avoidance learning.

Cerebral Glycoprotein Synthesis and Long-term Memory Formation in the Chick (Gallus domesticus) Following Passive Avoidance Training Depends on the Nature of the Aversive Stimulus

Chicks that peck a small bright bead coated in a distateful substance can learn in a single trial to subsequently avoid a similar bead. The taste aversant commonly used is methyl anthranilate, which also has a strong pervasive odour. We have compared the efficacy of methyl anthranilate and the apparently odourless quinine as aversants. Methyl anthranilate-trained chicks learnt the task and the memory apparently persisted undiminished for at least 24 h. Quinine-trained chicks exhibited a memory for the task similar to that of methyl anthranilate-trained chicks 45 min after training, this thereafter declined until, at 24 h after training, they showed no recall. We investigated the incorporation of a radio-labelled synaptic membrane glycoprotein precursor, [3H]fucose, into three regions of the chick forebrain; two of these regions have previously been implicated in learning using methyl anthranilate as the aversant. There was a significant increase in [3H]fucose incorporation into the left lateral cerebral area and numerically similar, but non-significant, increases in the intermediate part of the medial hyperstriatum ventrale and lobus parolfactorius. There were no such increases in the right hemisphere of methyl anthranilate-trained chicks or any region of either hemisphere of quinine-trained chicks. Thus, the memory for methyl anthranilate is longer-lasting than that for quinine and is associated with increased fucosylation in the left cerebral hemisphere and although in the short-term, chicks can retain a memory of the one-trial passive avoidance task with quinine as the aversant, this does not result in a localized increase in cerebral [3H]fucose incorporation.

An incentive plan for professional fee collections at an indigent-care teaching hospital

The authors describe the implementation and development of an incentive plan to improve professional fee collections at an indigent-care teaching hospital. They theorized that an incentive plan based on relative value unit (RVU) productivity would increase billings and collections of professional fees. Unique RVU targets were set for individual services based on the number of faculty full-time equivalents and average reported productivity for academic physicians by specialty. The incentive plan was based on the level of expected faculty billings, measured in RVUs, for each department. A "base + incentive" model was used, with the base budget being distributed monthly throughout the year, and the incentive held as a "withhold" to be paid at the year's end only if the billing target in RVUs was met. Additionally, a task force worked with physician billing office and the hospital to improve collections. In the first year after implementation of the system was in place, important increases were noted in total RVU productivity (30.5% over the previous year) and in collections (49.5% over the previous year). Sixteen of 23 departments exceeded their incentive targets, and it was possible to make distributions of professional fees to those departments, to be used within the hospital system to enhance clinical services. Moreover, the plan created an overall positive attitude toward billings and documentation of faculty activities. The authors believe that this kind of incentive plan will be increasingly important for academic faculty working in public hospital systems.

Outcomes and patient-based hearing status in conductive hearing loss

OBJECTIVES/HYPOTHESIS

To study hearing status and quality of life outcomes in patients with conductive hearing loss (CHL), and to develop a prognostic disease severity staging system for use in future clinical outcomes studies in CHL.

STUDY DESIGN

Clinical outcomes research study in three stages: 1) Prospective development and psychometric validation of a disease-specific hearing status outcomes instrument for CHL. 2) Prospective observational outcomes study of patient-based hearing status and quality of life (QOL) outcomes after treatment of CHL. 3) Development of a prognostic disease-severity staging system to stratify patients into groups of similar treatment outcome.

METHODS

Psychometric instrument validation: assessment of test-retest reliability, internal consistency reliability, content, construct and criterion validity, and responsiveness to change. Statistical assessment of the impact of CHL on patient-based hearing status and QOL, and the change in hearing status and QOL after treatment. Using data from the prospective study and multivariate regression, identification of pretreatment independent variables, which predict good outcome after treatment, and development of a severity staging system.

RESULTS

Test-retest reliability (r >0.70) and internal consistency reliability (alpha >0.70) were adequate for both subscales of the hearing status instrument. Construct validity was demonstrated by adequate convergent/divergent validity with other health status instruments on multi-item multitrait correlation matrixes. Criterion validity was demonstrated using audiometric threshold data. Responsiveness to change was demonstrated using the standardized response mean after treatment (SRM = 0.40 and 0.61 for the two subscales). Emotional hearing status and social/situational hearing status improved significantly after treatment of CHL: emotional score, 31.1 to 56.6 (P < .001); social/situational score, 56.7 to 63.7 (P = .01). Mean QOL subscale scores for patients with CHL were not significantly different from healthy populations, and global QOL scores did not change significantly after treatment of CHL. Using proportional improvement in emotional hearing status as an outcome, we identified several pretreatment factors that predicted good outcome (i.e., larger proportional improvement): level of pretreatment emotional hearing status, presence of sensorineural component of HL, and etiology of CHL (otosclerosis vs. all other causes). Some hypothesized predictive independent factors, such as bilateral HL, audiometric threshold level, pretreatment functional status, employment status, age, and duration of HL, were not identified as significant predictors of outcome in the multivariate analysis. We constructed a prognostic disease severity staging system in which the three predictor variables were each given a score of 0 or 1, and these three scores were added to obtain the disease stage (stage 0, 1, 2, or 3). Higher disease stage indicated more severe disease or a lower proportional improvement in emotional hearing status after treatment. This staging system appropriately stratified patients into groups of similar outcome after treatment (P = .02) and has significant potential use for future outcomes research on CHL.

CONCLUSIONS

We have developed and validated a patient-based hearing status outcomes instrument for use in CHL. We have measured hearing status and quality of life outcomes after treatment of CHL, and we have developed a prognostic disease severity staging system that predicts the improvement in emotional hearing status after treatment of CHL.

Ultrastructural distribution of the alpha7 nicotinic acetylcholine receptor subunit in rat hippocampus

Acetylcholine (ACh) is an important neurotransmitter in the mammalian brain; it is implicated in arousal, learning, and other cognitive functions. Recent studies indicate that nicotinic receptors contribute to these cholinergic effects, in addition to the established role of muscarinic receptors. In the hippocampus, where cholinergic involvement in learning and memory is particularly well documented, alpha7 nicotinic acetylcholine receptor subunits (alpha7 nAChRs) are highly expressed, but their precise ultrastructural localization has not been determined. Here, we describe the results of immunogold labeling of serial ultrathin sections through stratum radiatum of area CA1 in the rat. Using both anti-alpha7 nAChR immunolabeling and alpha-bungarotoxin binding, we find that alpha7 nAChRs are present at nearly all synapses in CA1 stratum radiatum, with immunolabeling present at both presynaptic and postsynaptic elements. Morphological considerations and double immunolabeling indicate that GABAergic as well as glutamatergic synapses bear alpha7 nAChRs, at densities approaching those observed for glutamate receptors in CA1 stratum radiatum. Postsynaptically, alpha7 nAChRs often are distributed at dendritic spines in a perisynaptic annulus. In the postsynaptic cytoplasm, immunolabeling is associated with spine apparatus and other membranous structures, suggesting that alpha7 nAChRs may undergo dynamic regulation, with insertion into the synapse and subsequent internalization. The widespread and substantial expression of alpha7 nAChRs at synapses in the hippocampus is consistent with an important role in mediating and/or modulating synaptic transmission, plasticity, and neurodegeneration.

Practice patterns versus practice guidelines in pediatric otitis media

OBJECTIVE

To study the practice patterns of physicians and their adherence to an evidence-based practice guideline (PG) on pediatric otitis media with effusion. We hypothesized that overall knowledge of the recommendations from the guidelines would be less than 75%, and that specialist physicians would have better knowledge of the recommendations than generalist physicians.

METHODS

We performed a survey study of 1167 otolaryngologists, pediatricians, and pediatric otolaryngologists. Each physician was sent a 6-item survey asking about their practice patterns and treatment preferences for young children with otitis media with effusion. We compared responses between different specialties.

RESULTS

The overall response rate was 48%. Only 8 (1.4%) of the 558 responding physicians answered all 6 items congruent with the PG. Overall, pediatricians, otolaryngologists, and pediatric otolaryngologists had similar total scores, but different scores on individual items.

CONCLUSIONS

These results indicate that the practice patterns of pediatricians, otolaryngologists, and pediatric otolaryngologists differ from the recommendations of an evidence-based PG. In particular, 2 items covering key treatment recommendations were answered in agreement with the PG by fewer than half of the physicians. It is not clear from this study whether these discrepancies were due to poor dissemination or knowledge concerning the PG, or disagreement with its recommendations.

Validation of a patient-graded instrument for facial nerve paralysis: the FaCE scale

OBJECTIVE

To develop and validate a patient-based instrument to measure both facial impairment and disability, the Facial Clinimetric Evaluation (FaCE) Scale.

STUDY DESIGN

Prospective instrument validation.

METHODS

Eighty-six patients with a documented history of facial paralysis completed a preliminary, 51-item instrument (alpha FaCE Scale), as well as the previously developed Facial Disability Index (FDI) and the Medical Outcomes Study Short Form 36 Item Questionnaire (SF-36). Two weeks after completing these instruments, 76 patients again completed the alpha FaCE Scale. Forty-one of the patients were also evaluated using the House-Brackmann Grading System (HBGS) and the Facial Grading System (FGS).

RESULTS

Exploratory principal component factor analysis grouped 15 FaCE Scale items into 6 impairment and disability categories (domains), forming the beta FaCE Scale. Overall, the test-retest reliability of the FaCE Scale was high (Spearman's correlation coefficient (r) = 0.88, P <.01), as were the reliability coefficients of the individual domains (r = 0.81-0.92, P <.01). The FaCE Scale domains showed appropriate correlation to global visual analogue scale questions posed on the original alpha FaCE Scale (r = 0.65-0.81, P <.01). Overall, the FaCE Scale showed significant correlation with HBGS and FGS scores (r = -0.55 and 0.57, respectively; P <.01). However, not all FaCE Scale domains correlated with the HBGS and FGS scores.

CONCLUSIONS

A reliable and valid patient-based system to measure impairment and disability in facial paralysis has been developed. This system appears to be better than traditional, physician-graded scales for evaluating quality-of-life issues affected by facial disability.

Re-structuring of synapses 24 hours after induction of long-term potentiation in the dentate gyrus of the rat hippocampus in vivo

In male rats, long-term potentiation was induced unilaterally in the dentate gyrus, either by high frequency (200Hz) or theta rhythm stimulation. Structural synaptic changes were examined 24h after induction using quantitative electron microscopy. A disector technique was employed in order to estimate the density of synapses (using 70-80-nm sections) and of granule cell nuclei (using 2-microm sections) in the middle, and inner molecular layer in both hemispheres. Synaptic height and total lateral areas of synaptic active zones per unit tissue volume were assessed via assumption-free stereological techniques coupled with image analysis. The results obtained indicated that both synaptic density and number (corrected per neuron) of axo-spinous, but not axo-dendritic, synapses were approximately 40% higher in the middle, but not inner molecular layer of the potentiated hemisphere compared to the contralateral (control hemisphere). No significant inter-hemispheric difference was found in the volume densities of lateral areas of active zones. These data suggest that 24h after long-term potentiation induction, active zones of existing axo-spinous synapses either split forming separate contacts, or decrease in size while new synapses are formed.

Validation of an outcomes instrument for tonsil and adenoid disease

OBJECTIVE

To design and validate a disease-specific health status instrument-the Tonsil and Adenoid Health Status Instrument-for use in children with tonsil and adenoid disease.

DESIGN

Prospective psychometric and clinimetric instrument validation in 3 stages.

SETTINGS

A tertiary academic pediatric specialty hospital and a tertiary academic hospital, in 2 different cities. PATIENTS/OTHER PARTICIPANTS: Children with tonsil and adenoid disease presenting for evaluation and treatment (n = 224). INTERVENTION/METHOD: Prospective instrument validation. Stage 1 consisted of initial item testing, reduction, and subscale construction; stage 2, reliability and validity testing, factor analysis, and final item reduction; and stage 3, responsiveness analysis.

MAIN OUTCOME MEASURES

Test-retest and internal consistency reliability; content, construct, and criterion validity; orthogonal principal components factor analysis; and response sensitivity analysis.

RESULTS

Factor analysis and item analysis confirmed 6 distinct subscales measuring different constructs (aspects) of disease-specific health status that are affected by tonsil and adenoid disease: eating and swallowing, airway and breathing, infections, health care utilization, cost of care, and behavior. For each subscale, the Tonsil and Adenoid Health Status Instrument demonstrated excellent test-retest reliability (r = 0.72-0.88) and internal consistency reliability (Cronbach alpha = .73-.87). Content validity was ensured during the design process. Construct validity was demonstrated by means of convergent and divergent validity with a global quality-of-life instrument (the Child Health Questionnaire, version PF28). Criterion validity was also satisfactory. Finally, the instrument was appropriately sensitive, with high standardized response means and effect sizes.

CONCLUSIONS

The Tonsil and Adenoid Health Status Instrument is a valid, reliable, and sensitive instrument with 6 distinct subscales. This instrument has significant utility for outcomes research in children with tonsil and adenoid disease.

Outcomes and quality of life in conductive hearing loss

OBJECTIVE

The goal was to measure quality of life (QOL) and hearing-specific functional status before and after treatment of conductive hearing loss (CHL).

STUDY DESIGN AND SETTING

A prospective, longitudinal, outcomes-based study was performed at an academic medical center.

RESULTS

Mean baseline QOL scores in CHL patients were comparable with those of the general population. Audiometric studies indicated significant improvements in hearing threshold in all treated patients. There was no significant improvement in mean global QOL scores after treatment of CHL, although there was little room for improvement over baseline. The hearing-specific instrument did demonstrate significant improvements in emotional and social/situational hearing status after treatment. Patients treated with hearing aids had poorer baseline QOL and hearing status than patients treated with surgery and tended to show declines in QOL and only partial improvement in hearing-specific functional status after treatment.

CONCLUSIONS

Treatment of CHL resulted in improvements in hearing-specific functional status, although changes were difficult to detect with a global QOL instrument.

Age-dependent pre- and postsynaptic distribution of AMPA receptors at synapses in CA3 stratum radiatum of hippocampal slice cultures compared with intact brain

Organotypic slice cultures of rat hippocampus are widely used as experimental preparations for the study of synaptic plasticity, but their degree of correspondence with intact brain is not fully known. Here, using postembedding immunogold labelling, we describe the ultrastructural distribution of AMPA-type glutamate receptors (GluR1-4) in CA3 stratum radiatum of organotypic hippocampal slice cultures at 10 days to 11 weeks in vitro and compare the labelling with intact brain of corresponding age. In both types of preparation, the 11-week-old samples contained the highest proportion of AMPA receptor-like immunoreactive synapses. The incidence of labelled synapses, however, was higher in vivo (49%) than in vitro (24%). The intensity of labelling (number of gold particles per labelled synapse) also increased with age and was also higher in vivo than in vitro. In both organotypic cultures and intact brain, labelling was frequently found at presynaptic sites, often attached to vesicular structures. The specificity of these findings was supported both by light microscopic immunolabelling of GluR2/3 subunits and by electron microscopic double labelling of different epitopes of the GluR2 subunit. The vesicular localization of AMPA receptors was supported by Western blot analysis of subcellular fractions. Morphological evidence of presynaptic excitatory innervation of glutamatergic neurons supports a functional role for presynaptically located AMPA receptors. Our results therefore suggest that AMPA receptors occur in both pre- and postsynaptic profiles and that the distribution of AMPA receptors in cultured brain slices is fundamentally similar to intact brain, but that synaptic maturation may be retarded in vitro.

Acute temporal bone trauma: utility of high-resolution computed tomography

OBJECTIVE

To determine the clinical utility of high-resolution computed tomography (HRCT) for temporal bone trauma evaluation and management.

STUDY DESIGN

Retrospective review.

SETTING

Level I trauma center.

PATIENTS

Patients (n = 105) with evidence of temporal bone trauma.

MAIN OUTCOME MEASURES

Statistically significant associations between HRCT, clinical, audiometric, and head CT findings, and management decisions; role of HRCT in management decisions.

RESULTS

Statistical analysis demonstrated poor association between specific clinical and HRCT findings, and between HRCT findings and management decisions. The HRCT complemented decision making in 10% of cases and revealed asymptomatic carotid canal fractures in 9% of cases.

CONCLUSION

Routine HRCT yields minimal clinical utility. Selective use of HRCT may complement decision making, but patient management is predominantly influenced by other factors. Although angiography was performed in cases of asymptomatic carotid canal fractures, no clinical utility for this practice was demonstrated. An algorithm for temporal bone trauma evaluation and management is presented.

Synaptic loss is accompanied by an increase in synaptic area in the dentate gyrus of aged human apolipoprotein E4 transgenic mice

To investigate the relationship between the three isoforms of apolipoprotein E (E2, E3 and E4) and the integrity of the synaptic circuitry in the dentate gyrus of the hippocampus, we have estimated the synapse per neuron ratio and mean apposition zone area per synapse at the electron microscope level in the dentate gyrus of apolipoprotein E knockout and human apolipoprotein E transgenic mice aged six to 24months. During ageing, only in human apolipoprotein E4 mice was there a decrease in synapse per neuron ratio, accompanied by an increase in synaptic size. When these mice were compared with human apolipoprotein E2, apolipoprotein E knockout and wild-type mice at old age, they displayed the lowest synapse per neuron ratio, but similar apposition zone area. In contrast, as in our previous study, aged apolipoprotein E knockout mice did not show any sign of synaptic degeneration. The functional consequences of such morphological changes remain to be determined. However, if such age-related loss of synapses occurred in the brain of Alzheimer apolipoprotein E4 patients, they might be additive to pathological processes and could contribute to greater cognitive impairment.

Does the severity of sinus computed tomography findings predict outcome in chronic sinusitis?

OBJECTIVES

We studied the association between the severity of pretreatment CT scan findings and the improvement in symptoms of chronic sinusitis after treatment.

METHODS

We analyzed data from an ongoing prospective, nonrandomized clinical outcomes study of patients treated for chronic sinusitis at a tertiary-care academic medical center (n = 57, mean age 46.8 years). Disease-specific symptom severity was measured with a validated health status instrument, and CT stage was quantified with the Harvard CT staging system.

RESULTS

In a multivariate analysis, symptom severity based on CT findings emerged as a strong predictor of both improvement in symptom score outcome (beta = 0.47, P = 0.01) and absolute symptom level after treatment (beta = -0.58, P = 0.001).

CONCLUSIONS

Severity as assessed by a pretreatment CT scan is a strong predictor of outcome. Patients with higher symptom severity based on CT scans showed significantly larger improvement and lower absolute levels of symptom severity after treatment. This study links CT scan findings and subjective patient-based outcomes (symptom scores) using a validated outcomes instrument.

Unrecognized benign paroxysmal positional vertigo in elderly patients

Balance disorders in elderly patients are associated with an increased risk of falls but are often difficult to diagnose because of comorbid chronic medical problems. We performed a cross-sectional study to determine the prevalence of unrecognized benign paroxysmal positional vertigo (BPPV) and associated lifestyle sequelae in a public, inner-city geriatric population. Dizziness was found in 61% of patients, whereas balance disorders were found in 77% of patients. Nine percent were found to have unrecognized BPPV. Multivariate analysis demonstrated that the presence of a spinning sensation and the absence of a lightheadedness sensation predicted the presence of unrecognized BPPV. Patients with unrecognized BPPV were more likely to have reduced activities of daily living scores, to have sustained a fall in the previous 3 months, and to have depression. These data indicate that unrecognized BPPV is common within the elderly population and has associated morbidity. Further prospective studies are warranted.

Quality of life and disease-specific functional status following microvascular reconstruction for advanced (T3 and T4) oropharyngeal cancers

In an effort to evaluate quality-of-life benefits of ablative head and neck cancer surgery and microvascular reconstruction, a longitudinal study was undertaken in which patients with T3 or T4 oropharyngeal cancers without systemic metastases at presentation were administered both general and disease-specific quality-of-life instruments preoperatively and postoperatively. In an initial prospective pilot study, 17 cancer patients were evaluated both preoperatively and postoperatively using the Medical Outcomes Short-Form Health Survey questionnaire (SF-36) and the Performance Status Scale for Head and Neck Cancer Patients. In the second part of the study, the need was recognized for a different disease-specific measure, for more frequent intervals of longitudinal follow-up (rather than be limited by a single data collection point), and for a noncancer control group. Since then, 17 more cancer patients were evaluated in the second part of the study and were compared with patients who had similar reconstructions after suffering head and neck trauma and also with age-matched controls. Instead of the performance status scale, the University of Washington Head and Neck Quality of Life questionnaire was substituted. Interval assessments were done at 1, 3, 6, and 12 months and preoperatively. Whereas many of the general and disease-specific quality of life subclasses initially worsened following extensive surgery and radiation therapy, most returned to the preoperative baseline by 6 months following conclusion of treatment and surpassed pretreatment values at 1 year. It can be concluded, based on this study, that large resections and reconstructions for head and neck cancer patients are justified in terms of outcome; the resection controls the local disease, and the microvascular reconstruction restores quality of life and functional status.