Ultrathin thermoacoustic nanobridge loudspeakers from ALD on polyimide.

The recent development of low-temperature (<200 °C) atomic layer deposition (ALD) for fabrication of freestanding nanostructures has enabled consideration of active device design based on engineered ultrathin films. This paper explores audible sound production from thermoacoustic loudspeakers fabricated from suspended tungsten nanobridges formed by ALD. Additionally, this paper develops an approach to lumped-element modeling for design of thermoacoustic nanodevices and relates the near-field plane wave model of individual transducer beams to the far-field spherical wave sound pressure that can be measured with standard experimental techniques. Arrays of suspended nanobridges with 25.8 nm thickness and sizes as small as 17 µm × 2 µm have been fabricated and demonstrated to produce audible sound using the thermoacoustic effect. The nanobridges were fabricated by ALD of 6.5 nm Al2O3 and 19.3 nm tungsten on sacrificial polyimide, with ALD performed at 130 °C and patterned by standard photolithography. The maximum observed loudspeaker sound pressure level (SPL) is 104 dB, measured at 20 kHz, 9.71 W input power, and 1 cm measurement distance, providing a loudspeaker sensitivity value of ∼64.6 dB SPL/1 mW. Sound production efficiency was measured to vary proportional to frequency f 3 and was directly proportional to input power. The devices in this paper demonstrate industrially feasible nanofabrication of thermoacoustic transducers and a sound production mechanism pertinent to submicron-scale device engineering.

Manipulating walking path configuration influences gait variability and six-minute walk test outcomes in older and younger adults.

This study determined whether manipulations to walking path configuration influenced six-minute walk test (6MWT) outcomes and assessed how gait variability changes over the duration of the 6MWT in different walking path configurations. Healthy older (ODR) and younger (YNG) (n=24) adults completed familiarisation trials and five randomly ordered experimental trials of the 6MWT with walking configurations of; 5, 10 and 15m straight lines, a 6m by 3m rectangle (RECT), and a figure of eight (FIG8). Six-minute walk distance (6MWD) and walking speed (m.s(-1)) were recorded for all trials and the stride count recorded for experimental trials. Reflective markers were attached to the sacrum and feet with kinematic data recorded at 100 Hz by a nine-camera motion capture system for 5m, 15m and FIG8 trials, in order to calculate variability in stride and step length, stride width, stride and step time and double limb support time. Walking speeds and 6MWD were greatest in the 15m and FIG8 experimental trials in both groups (p<0.01). Step length and stride width variability were consistent over the 6MWT duration but greater in the 5m trial vs. the 15m and FIG8 trials (p<0.05). Stride and step time and double limb support time variability all reduced between 10 and 30 strides (p<0.01). Stride and step time variability were greater in the 5m vs. 15m and FIG8 trials (p<0.01). Increasing uninterrupted gait and walking path length results in improved 6MWT outcomes and decreased gait variability in older and younger adults.

Study of the interaction of the medium chain mu 2 subunit of the clathrin-associated adapter protein complex 2 with cytotoxic T-lymphocyte antigen 4 and CD28.

The medium chain mu 2 subunit (AP50) of the clathrin-associated adapter protein complex 2 (AP-2) interacts specifically with the tyrosine-based signals of several integral membrane proteins through the consensus sequence YXXPhi, where X can be any residue and Phi is a large hydrophobic residue. Using surface plasmon resonance combined with structural information, we have analysed the interaction of AP50 with peptides derived from the cytoplasmic tail of cytotoxic T-lymphocyte antigen 4 (CTLA-4). The crystal structure of AP50 in complex with a CTLA-4-derived peptide was determined to 3.6 A (1 A=0.1 nm) resolution. The binding domain of AP50 (residues 164-435) was expressed in Escherichia coli and purified. In agreement with previous reports, the AP50 domain bound to residues 152-174 of CTLA-4, but not to the same peptide that was phosphorylated at the single tyrosine residue (position 165). The interaction exhibited fast kinetics with rapid on and off rates and a K(d) of 0.7 microM. In order to further understand why AP50 binds to CTLA-4, but not to the homologous receptor CD28, a comparison of binding of AP50 with five peptides with single changes in and around the YXXPhi motif to the equivalent residues of CD28 was made. T162H greatly reduced binding, whereas T161L had little effect. Mutations G163S, V164D and K167N all exhibited reduced binding. Modelling of the single amino acid changes using structural information, was in broad agreement with the binding data, demonstrating that residues outside of the YXXPhi motif are also important in the interaction of membrane proteins with AP50.

Tardive dyskinesia--diagnostic issues, subsyndromes, and concurrent movement disorders: a study of state hospital inpatients referred to a movement disorder consultation service.

Of 49 state hospital patients referred for movement disorder consultation for tardive dyskinesia (TD), 11 (23.9%) of 46 meeting inclusion criteria had movement disorders other than TD. These other disorders led to a false diagnosis of TD in 6 subjects (12.2%). Between-day dyskinesia variability affected TD ascertainment in only 3.2 percent of subjects. Prevalences of other neurological conditions in the 30 patients identified with definite TD were parkinsonism (90%), dystonia (25%), akathisia (16%), cerebellar signs (40%), dysmetria (23%), cerebellar tremor (17%), tardive dystonia (3.3%), and tardive akathisia (3.3%). Concurrence rates of parkinsonism with TD varied significantly according to which clinical signs were used to define parkinsonism. Using a rating score threshold of at least mild, rigidity occurred in 79.3 percent, bradykinesia in 55.2 percent, and resting tremor in 41.4 percent of subjects with TD; more significant rigidity occurred in 41.4 percent, bradykinesia in 31.0 percent, and resting tremor in 20.7 percent. Concurrence rates of neurological conditions with TD subsyndromes were distributed rather evenly according to condition prevalences, except for an association of cervicotruncal TD with bradykinesia (perhaps because of ventromedial striatal presynaptic and postsynaptic D2 blockade, respectively). These findings, as well as the occurrence of equal gender ratio and relative under-representation of bipolar and alcohol disorders in subjects with definite TD, are discussed.

Heptad-repeat regions of respiratory syncytial virus F1 protein form a six-membered coiled-coil complex.

The Respiratory Syncytial Virus (RSV) fusogenic glycoprotein F(1) was characterized using biochemical and biophysical techniques. Two heptad-repeat (HR) regions within F(1) were shown to interact. Proteinase-K digestion experiments highlight the HR1 region (located proximal to the fusion peptide sequence) of the F(1) protein to which an HR2-derived (located proximal to the membrane-spanning domain) peptide binds, thus protecting both the protein and peptide from digestion. Solution-phase analysis of HR1-derived peptides shows that these peptides adopt helical secondary structure as measured by circular dichroism. Sedimentation equilibrium studies indicate that these HR1 peptides self-associate in a monomer/trimer equilibrium with an association constant of 5.2 x 10(8) M(-2). In contrast, HR2-derived peptides form random monomers in solution. CD analysis of mixtures containing peptides from the two regions demonstrate their propensity to interact and form a very stable (T(m) = 87 degrees C), helical (86% helicity) complex comprised of three HR1 and three HR2 members.

A review of EEG biofeedback treatment of anxiety disorders.

Alpha, theta and alpha-theta enhancements are effective treatments of the anxiety disorders (Table 1). Alpha suppression is also effective, but less so (Table 2). Perceived success in carrying out the task plays an important role in clinical improvement. Research is needed to find out how much more effective they are than placebo, and which variables are important for efficacy. Variables needing study are: duration of treatment, type and severity of anxiety, number and type of EEG waveforms used, pretreatment with other kinds of feedback, position and number of electrodes, and presence of concomitant medication.

Intrathymic expression of genes involved in organ specific autoimmune disease.

Insulin, thyroglobulin and myelin basic protein (MBP) are implicated as autoantigens in the autoimmune diseases, insulin-dependent diabetes mellitus (IDDM), autoimmune thyroid-disease and multiple sclerosis. Self tolerance to these antigens, until recently only thought to be present extrathymically, is generally considered to be maintained by 'peripheral' mechanisms, such as clonal anergy or clonal ignorance. The techniques of reverse transcription and polymerase chain reaction (RT-PCR) were used to investigate the intrathymic expression of these genes. Expression was examined in mRNA isolated from complete adult rat thymus, various mouse thymic cell-types isolated from fetal thymic-organ cultures and from neonatal-mouse thymocyte subsets. mRNA for insulin, thyroglobulin and MBP were detected in unfractionated adult rat and embryonic mouse thymus. Rat thymus expressed both insulin I and II, while mouse thymus only expressed insulin II. Thyroglobulin and MBP, but not insulin mRNA were detected in mouse MHC class II+ thymic epthelial cells and class II+ dendritic cells and in certain thymocyte subsets. The presence of insulin, thyroglobubin and MBP mRNA in the thymus has important implications for the development of the T-cell repertoire, particularly for the mechanisms of tolerance that prevent autoreactivity to these antigens in healthy individuals.

P300 delay and attenuation in schizophrenia: reversal by neuroleptic medication.

BACKGROUND: P300 amplitude reduction in schizophrenia has been found by many investigators, but P300 latency generally has been reported to be normal; however, conflicting findings are present in the literature, and interpretation has been confounded by medication effects and methodological differences. METHODS: This study used a standard auditory oddball paradigm to compare the latency, amplitude, and topographic distribution of P300s in neuroleptic-free schizophrenic patients with those of healthy controls. The patients then were treated for 6 weeks with either remoxipride or haloperidol, and their P300s were reassessed. RESULTS: P300s were attenuated and delayed among neuroleptic-free patients. There was no evidence of peak lateralization or amplitude asymmetry over temporal areas. Subsequent neuroleptic medication normalized P300 latencies and increased P300 amplitudes, but the latter remained below normal limits over all except frontal areas. There were no correlations between P300 latency or amplitude and clinical symptomatology either before or after treatment. CONCLUSIONS: The finding of a P300 delay in neuroleptic-free schizophrenics that is normalized by neuroleptic medication has not been reported previously. Neuroleptic effects on P300 amplitude and latency appear to be independent of effects on clinical symptoms, and cannot be attributed to anticholinergic activity.

Induction of apoptosis in thecal/interstitial cells: action of transforming growth factor (TGF) alpha plus TGF beta on bcl-2 and interleukin-1 beta-converting enzyme.

Follicular atresia is characterized by the initial rapid loss of granulosa cells by apoptosis, followed by the loss of thecal cells at a slower rate. We have previously shown that treatment of subconfluent cultures of thecal/interstitial cells (T/I) with transforming growth factor (TGF) alpha plus TGF beta caused chromatin condensation and internucleosomal fragmentation characteristic of apoptosis, whereas in the presence of either TGF alpha or TGF beta alone the cells remained healthy. In this study we have examined the effect of TGF alpha and TGF beta alone and in combination on the levels of mRNA encoding bcl-2 and interleukin-1 beta-converting enzyme (ICE) in T/I cells using a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay. Bcl-2, a cell survival gene, has been implicated in regulating the balance between cell proliferation and cell death in physiological processes. ICE, the homolog of the C. elegans cell death gene, ced-3, is also involved in apoptotic signal transduction. The levels of mRNA encoding specific PCR products for bcl-2 (430 bp) and ICE (453 bp) were amplified from T/I cell cDNA. Untreated T/I cells and TGF alpha- or TGF beta-treated cells contained comparable levels of bcl-2 mRNA. Treatment of T/I cells with TGF alpha plus TGF beta significantly decreased the levels of bcl-2 mRNA expression. TGF alpha plus TGF beta caused a significant decrease in bcl-2 mRNA levels within 3 h of treatment of T/I cells, followed by a progressive decline to 10% of control levels after 24 h of treatment. In contrast, in control T/I cells, the levels of ICE mRNA were low. TGF alpha plus TGF beta caused a progressive increase in ICE mRNA, reaching levels 2- and 3-fold higher than control cells after 5 and 7 h respectively. DNA analysis showed that DNA fragmentation, indicative of apoptosis, occurred after 10 h of treatment with TGF alpha plus TGF beta. These studies demonstrated that treatment of T/I cells with TGF alpha plus TGF beta influenced gene expression of bcl-2 and ICE prior to the time at which DNA fragmentation was observed. We propose that the gene products of bcl-2 and ICE are involved in the apoptotic signal transduction pathway induced by TGF alpha plus TGF beta in T/I cells.

Studies on thymic epithelial cells in vitro.

Thymic epithelial cells are unique in their ability to support positive selection and are essential throughout thymocyte development. Here, we describe a technique for measuring the proliferation of thymic epithelial cells by flow cytometry using a combination of BrdU and pancytokeratin labelling, and we examine the effects of different in vitro culture strategies on thymic epithelial cell function. We find that at d15 gestation, 74% (+/- 0.4%) of thymic epithelial cells are in cycle, which declines to 63% (+/- 1.3%) by d16, and to 34% (+/- 1.9%) by d18. This decline in proliferation is also found in organ cultures and in cultures depleted of lymphoid cells by 2-dGuo, suggesting that the cell cycle status of thymic epithelial cells is independent of the lymphoid population. When cultured in vitro as 3-dimensional aggregates, purified MHC class II+ thymic epithelial cells retain the ability to support thymocyte maturation. In contrast, 2-dimensional monolayer culture abrogates the ability of these cells to support positive selection, causes a reduction in whn gene expression and reduces their ability to re-form coherent reaggregate structures. Intact lobes and 3-dimensional aggregates are therefore the best way of maintaining thymic epithelial cell function and gene expression in vitro.

Visual evoked responses in Alzheimer's disease: a review.

This review of the literature has shown that a delayed flash P2, in the presence of a normal flash P1 and pattern-reversal P100, can distinguish groups of Alzheimer's patients from groups who are healthy, psychiatrically ill, or suffering from other types of dementia. The VER's usefulness in the individual patient remains undetermined. With today's techniques, too many patients are misclassified. False negatives may result if Alzheimer's patients with visual symptoms are a distinct subgroup. Those with a normal flash VER may have cortical dysfunction outside the visual association areas. This would most likely be in the earliest stages of the disease before the atrophy becomes widespread. It may be that a VER test would only be valid in established disease. Future research should use adequate numbers of patients who are in a single category of mild, moderate or severe, so that the applicability of a VER test in the early stages of the disease can be determined. Strict diagnostic criteria such as the NINCDS-ADRDA guidelines should be used. Patients should be drug free, or at least not taking medications with anticholinergic properties. Flash VER should be obtained using a strobe light with eyes closed, and the pattern VER using a black and white television with a large pattern and high contrast.

Involvement of LFA-1/ICAM-2 adhesive interactions and PKC in activation-induced cell death following SEB rechallenge.

Ligation of T-cell receptor (TCR) causes mature T cells to proliferate or, on re-exposure to antigen, can cause them to die by activation-induced cell death (AICD). In proliferative responses, costimulatory and adhesive interactions are required and activation of protein kinase C (PKC) has been shown to be essential. Whether or not interactions involving costimulatory signals and PKC have a role in facilitating AICD remains unclear. Here we have examined the role of CD28/B7 and leucocyte function associated antigen-1 (LFA-1)/intracellular adhesion molecule (ICAM) mediated interactions in AICD triggered by staphylococcal enterotoxin B (SEB) in murine lymph node T cells. We show that, after a primary proliferative response to SEB, LFA-1/ICAM-2 adhesive interactions can play a part in AICD following SEB rechallenge, while B7 and ICAM-1 mediated interactions are not essential for this process. In addition, using a highly selective PKC inhibitor, Ro31.8425, we show that PKC activation is essential for the regulation of AICD by SEB rechallenge.

The role of the thymus in the control of autoimmunity.

Self tolerance among T cells is believed to be maintained by two principal mechanisms: clonal deletion for self antigens expressed in the thymus and T cell anergy or T cell indifference for those whose expression is solely extrathymic. These mechanisms are passive in that they depend on autoreactive T cells being either eliminated during their maturation or rendered intrinsically non-responsive after they have matured. The data presented in this paper indicate that this scheme requires modification. First, it is evident that self antigens that are commonly regarded as being tissue-specific may also be expressed in the thymus where they influence the developing T cell repertoire. Second, it appears that there is some T cell-mediated regulatory mechanism that actively prevents potentially autoreactive T cells from expressing their disease-inducing potential. Our data indicate that this regulatory mechanism is established intrathymically and is an innate property of the naive T cell repertoire. The mechanism is discussed in terms of what is currently known of the ways that an individual T cell responds when interacting with agonist and antagonist peptides and possible therapeutic implications are considered.

Nitric oxide synthase (NOS) in schizophrenia: increases in cerebellar vermis.

A high proportion of neurons in the cerebellum and in cholinergic brainstem nuclei stain positive for nicotinamide adenine dinucleotide phosphate-diaphorase (NADPHd), which is a nitric oxide synthase (NOS). Recent evidence suggests that schizophrenia may involve increased numbers of NADPHd-stained neurons in different areas of the subcortex. This led us to examine the actual concentration of NOS in postmortem brain specimens of cerebellum, and the relevant regions of brainstem tegmentum, to see if NOS concentrations were also increased in schizophrenia. Postmortem brain tissue was obtained at autopsy from schizophrenics and controls who did not have other brain disease. In patients with schizophrenia, NOS concentration was higher.

Cellular interactions in thymocyte development.

Interactions between stromal cells and thymocytes play a crucial role in T cell development. The thymic stroma is complex and consists of epithelial cells derived from the pharyngeal region during development, together with macrophages and dendritic cells of bone marrow origin. In addition, fibroblasts and matrix molecules permeate the whole framework. It is now apparent that these individual stromal components play specialized roles at different stages of T cell differentiation. Thus, at the early CD4-8- stage of development, T cell precursors require fibroblast as well as epithelial cell interactions. Later, at the CD4+8+ stage, as well as providing low avidity TCR/MHC-peptide interactions, thymic epithelial cells have been shown to possess unique properties essential for positive selection. Dendritic cells, on the other hand, are probably efficient mediators of negative selection, but they may not be solely responsible for this activity. Alongside the functional roles of stromal cells, considerable progress is being made in unraveling the nature of the signaling pathways involved in T cell development. Identification of the pre-T cell receptor (pre-TCR) and associated signaling molecules marks an important advance in understanding the mechanisms that control gene rearrangement and allelic exclusion. In addition, a better understanding of the signaling pathways that lead to positive selection on the one hand and negative selection on the other is beginning to emerge. Many issues remain unresolved, and some are discussed in this review. What, for example, is the nature of the chemotactic factor(s) that attract stem cells to the thymus? What is the molecular basis of the essential interactions between early thymocytes and fibroblasts, and early thymocytes and epithelial cells? What is special about cortical epithelial cells in supporting positive selection? These and other issues are ripe for analysis and can now be approached using a combination of modern molecular and cellular techniques.

P2 flash visual evoked response delay may be a marker of cognitive dysfunction in healthy elderly volunteers.

In an earlier study, 31 healthy elderly volunteers had normal cognitive function as measured by the Mini-Mental State Examination. Twenty-seven returned for further memory testing using the Wechsler Memory Scale-Revised (WMS-R). The P2 latency of the flash visual evoked response was positively correlated with age (p = .0008), but was not significantly related to gender. Nine of these 27 putatively healthy subjects had a delayed P2, suggestive of dementia. Although unaware of any memory deficits, 5 of the 27 had WMS-R Visual Memory Span percentile scores 1 or more standard deviations less than age-matched controls. Four of the five also had a significantly delayed P2 component. This positive correlation, adjusted for age, between poor Visual Memory Span performance and a delayed P2 was statistically significant (p < .025). These findings suggest that a delayed P2 in putatively healthy subjects is indicative of a visuospatial deficit which might be a precursor of dementia later.

Stimulation of thymocytes before and after positive selection results in the induction of different NF-kappa B/Rel protein complexes.

Positive selection triggers the differentiation of immature CD4+8+TCRlow thymocytes into TCRhigh single-positive CD4+ or CD8+ cells and is associated with major changes in gene expression. However, little is known about the DNA binding factors controlling these fundamental changes. Here we have examined NF-kappa B/Rel subunit expression and DNA-binding activity in developing thymocytes before and after the induction of positive selection. We show that positive selection is accompanied by the strong up-regulation of c-rel mRNA expression and the constitutive activation of p50/p65 and p50/c-Rel NF-kappa B/Rel complexes, confirming the activation-like status of cells undergoing positive selection. Moreover, CD69+ cells that have initiated positive selection (but not their preselection CD4+8+TCR- precursors) respond to stimulation by the preferential activation of c-Rel-containing DNA-binding complexes. Because the different NF-kappa B/Rel dimers have distinct transcriptional activities and binding site preferences, this preferential activation of c-Rel-containing DNA-binding complexes may well have implications for the changes in gene expression and functional response associated with positive selection.