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PubMed1985

Apperceptive agnosia due to carbon monoxide poisoning. An interpretation based on critical band masking from disseminated lesions.

Apperceptive visual agnosia is normally held to be a specific deficit in 'apperception' - a hypothetical postsensory stage in visual processing. This paper describes the investigation of a patient diagnosed as suffering from a classical apperceptive agnosia resulting from carbon monoxide poisoning. Controlled behavioural testing confirmed the apparent agnosia but revealed that he could be trained to make a number of visual discriminations which had not been apparent from routine clinical examination and that he suffered a number of subtle sensory impairments which likewise had not hitherto been apparent. Evoked potential recording to grating patterns showed a complex pattern of brain responses involving interactions between spatial frequency, orientation and hemisphere recorded from. The data suggested that the agnosia was caused by sensory impairments rather than a deficit in apperception. We proposed that the impairments were caused by loss of certain spatial frequency and orientation information but rejected an interpretation based on the concept of processing channels in favour of one based on object contour masking by a peppery field defect caused by disseminated lesions. This interpretation received some support from fine grain static perimetry, contrast sensitivity function measurement and orientation discrimination in the two hemifields. Qualitatively similar results were obtained in normal subjects whose field was artificially masked. The results have implications for theories of visual agnosia and for theories of vision based on the concept of processing channels.

Agnosia↗

PubMed1993

Selective attention and brainstem frequency-following responses.

In the auditory system, cortical event-related potential amplitudes are enhanced during selective attention within the auditory channel. In the case of brainstem responses, however, the results are less clear since only a few studies have reported attention effects. Nearly all of these studies have used click stimuli to elicit the brainstem auditory evoked response (BAER). In the present study, pure tones (200 and 400 Hz) elicited the brainstem frequency-following response (FFR) in a task that maximized channel separation by presenting different frequencies to each ear. Twelve male and 12 female subjects participated. Perceptual sensitivity (d') showed an overall right ear advantage (REA) that did not depend on gender or stimulus frequency. FFR averages were enhanced by digital filtering, the 25 ms response was partitioned in half, and quantified by fast-Fourier analysis. Results of the statistical analysis showed a significant Attention x Frequency x Half interaction. Thus, whether or not component amplitudes were larger during attention depended on the particular stimulus and temporal location within the FFR. These results are more complex and time variant than would be predicted by the hypothesis that attention only enhances evoked response amplitudes. Nevertheless, these results suggest that some form of attention-related modulation may be occurring at the level of the brainstem. The present results provide additional support for a peripheral gating mechanism in humans, which has been claimed in a minority of BAER studies. The FFR may provide additional useful information since it presumably depends on phase-locking neural elements, rather than on-units activated by acoustic transients.

Adult↗

PubMed1982

Spectro-temporal characteristics of single units in the auditory midbrain of the lightly anaesthetised grass frog (Rana temporaria L.) investigated with tonal stimuli.

Responses were obtained from 112 auditory neurons in the midbrain of the grass frog in response to sequences of tones. Their spectro-temporal sensitivities (STS) were determined by a second-order cross-correlation technique. For the majority of units the shape of their action potentials, the degree of timelock to the stimulus and the recording sites were obtained. Two stages of information processing could be distinguished. One was characterized by short latencies (less than 30 ms), strong timelock to the stimulus and many of these units had axon-like action potential waveforms. They were localised in the ventral part of the principal nucleus from the torus semicircularis and in the transition region between laminar and principal nucleus. The other stage comprised units, found all over the torus, with longer latencies, and a weaker timelock to the stimulus. Several units which were predominantly found in the central part of the torus, especially the magnocellular nucleus, showed a broad or multiple STS. Within the principal nucleus a weak tonotopy was found, the dorsoposterior part being sensitive to lower frequencies, the ventroanterior part to the higher frequencies. Binaural-interaction properties are discussed with respect to the eardrum coupling through the mouth cavity. An organisational plan for the torus semicircularis is proposed.

Acoustic Stimulation↗

PubMedDate not supplied

Development and evaluation of the Active Treatment Client Rights Checklist.

The role of active treatment has been recognized as vital to the habilitation of persons with mental retardation; however, evaluating the provision of active treatment has been difficult. This study describes the development of the Active Treatment Client Rights checklist (ATCR), which was designed to facilitate the assessment, monitoring, and implementation of readily observable client active treatment services. This investigation provides an explanation of item content, initial reliability data (Phase I), and the results of implementation of the ATCR over a 2-year period in an ICF/MR facility with 29 living units serving nearly 500 clients (Phase II). The ATCR is highly reliable, valid, and useful in enhancing staff provision of active treatment. The most sensitive indicator of active treatment was shown to be related to frequency of functional interactions between clients and staff.

Activities of Daily Living↗

PubMed2006

Dendritic cell-based immunogens for B-cell chronic lymphocytic leukemia.

Hybrids generated from tumor cells and dendritic cells (DC) have been proposed as tools for treating malignant disease. Here, we study the underlying principles and the feasibility for the adjuvant therapy of human B cell chronic-lymphocytic leukemia (B-CLL). CLL cells and allogeneic DC were only mixed or additionally fused. Using a combination of FACS and fluorescence microscopic analyses, we show that DC-CLL hybrids can be successfully generated. However, fusion frequencies have to be critically evaluated because the number of fused cells is overestimated when based on FACS analyses alone. The capability of activating patients' PBMC was examined by measuring cytokine secretion in co-culture assays. We made a systematic comparison of the immunostimulatory capacities of different stimulator cell populations, including DC-CLL fusion samples, unfused mixtures of DC and CLL cells as well as DC or tumor cells alone. Surprisingly, even unfused mixtures had a pronounced tumor-directed immunostimulatory effect. This could be explained by the capture of antigens from surrounding leukemia cells by DC during co-cultivation. Although fusion frequencies were low, PBMC stimulation was significantly more effective when the mixtures were subjected to cell fusion. The most potent stimulus was provided by DC-CLL fusion samples derived from mature DC, probably due to their enhanced costimulatory capacity. In summary, DC-tumor cell hybrids might be feasible in the treatment of B-CLL. It should be considered that FACS analysis is not sufficient to assess fusion frequencies and that interactions between unfused DC and CLL cells also result in PBMC activation.

Aged↗

PubMed2005

Factors influencing farmers' concerns regarding bovine tuberculosis in wildlife and livestock around Riding Mountain National Park.

Despite intensive efforts over the last century to eradicate bovine tuberculosis (TB) in North America, several hotspots of infected wildlife and livestock remain, raising concerns that the disease will never be eradicated. The stress and frustration for a farmer caused by having a herd test positive for TB or living in an infected region can be substantial. The goal of this study was to investigate the concerns of farmers around Riding Mountain National Park (RMNP) regarding the presence of TB in wildlife and livestock and conduct an exploratory analysis of causal factors. Data were collected from 786 farmers within 50 km of RMNP using a mail-back questionnaire. Overall, farmers indicated a high level of concern toward diseases in both wildlife and cattle relative to other concerns. The spatial variables that had the greatest influence on TB concern were both the distance of farms to the RMNP boundary and distance of farms to previous cases of TB. The most important aspatial factor associated with high TB concern was the frequency with which farmers observed elk on their land. These results underscore the important differences between 'objective' measures of risk, such as epidemiological estimates of disease prevalence, and subjective measures of disease concern, such as risk perception and acceptability of management actions. Written responses suggest that concerns regarding disease may affect how farmers view wildlife on their land and their relationship with neighbouring protected areas. Management activities that reduce the frequency of elk interactions with farms, but also recognize the complex relationship that farmers have with wildlife and protected areas, will be most effective in mitigating farmer concern regarding this important problem.

Agriculture↗

PubMed2006

Selective detection of ordered sodium signals via the central transition.

Given the correlation between the concentrations of ordered (23)Na and the onset of tissue disorders, the ability to select the signal from ordered (23)Na over that of free (23)Na is of particular importance and can greatly enhance the potential of (23)Na-MRI as a diagnostic tool. Here, we describe a simple method that selectively detects the central transition of ordered sodium while minimizing the signal from free sodium. Our method relies upon the influence of the quadrupolar interaction on nutation frequencies and may also benefit solid-state imaging experiments. Both a liquid crystalline environment and a cartilage sample are used to demonstrate a clean separation between anisotropic and isotropic regions in the experiments.

Animals↗

PubMed2006

Reliability of speaking and maximum voice range measures in screening for dysphonia.

Speech range profile (SRP) is a graphical display of frequency-intensity occurring interactions during functional speech activity. Few studies have suggested the potential clinical applications of SRP. However, these studies are limited to qualitative case comparisons and vocally healthy participants. The present study aimed to examine the effects of voice disorders on speaking and maximum voice ranges in a group of vocally untrained women. It also aimed to examine whether voice limit measures derived from SRP were as sensitive as those derived from voice range profile (VRP) in distinguishing dysphonic from healthy voices. Ninety dysphonic women with laryngeal pathologies and 35 women with normal voices, who served as controls, participated in this study. Each subject recorded a VRP for her physiological vocal limits. In addition, each subject read aloud the "North Wind and the Sun" passage to record SRP. All the recordings were captured and analyzed by Soundswell's computerized real-time phonetogram Phog 1.0 (Hitech Development AB, Täby, Sweden). The SRPs and the VRPs were compared between the two groups of subjects. Univariate analysis results demonstrated that individual SRP measures were less sensitive than the corresponding VRP measures in discriminating dysphonic from normal voices. However, stepwise logistic regression analyses revealed that the combination of only two SRP measures was almost as effective as a combination of three VRP measures in predicting the presence of dysphonia (overall prediction accuracy: 93.6% for SRP vs 96.0% for VRP). These results suggest that in a busy clinic where quick voice screening results are desirable, SRP can be an acceptable alternate procedure to VRP.

Adult↗

PubMed2005

Effect of specific aspects of community social environment on the mortality of individuals diagnosed with serious illness.

The purpose of this study was to examine the prospective and contextual effects of urban community environment on mortality among Medicare beneficiaries who were 67 years old or older in 1993, lived in the city of Chicago, and were hospitalized for one of 13 serious diseases. As expected, we found that advantageous socioeconomic context helps lower mortality risk among elderly patients over and above individual demographic and health background. We also found that collective efficacy was a health-enhancing social resource whereas criminal and violent activities in the community appeared to be deleterious. Inconsistent with our hypotheses, community social network density (measured by the size of social network and frequency of social interaction) was not protective but detrimental. Moreover, social support and the civic involvement of residents in the community do not seem to affect mortality. The complex relationship between community social environment and health found in this study may suggest that community-level social interventions based on social capital/social cohesion models are not likely to achieve fruitful results without concomitant effort in the economic and health care realm, at least in terms of influences on the health of older people once they are already ill.

Acute Disease↗

PubMed2006

Channel surfing in the visual brain.

Vision provides us with an ever-changing neural representation of the world from which we must extract stable object categorizations. We argue that visual analysis involves a fundamental interaction between the observer's top-down categorization goals and the incoming stimulation. Specifically, we discuss the information available for categorization from an analysis of different spatial scales by a bank of flexible, interacting spatial-frequency (SF) channels. We contend that the activity of these channels is not determined simply bottom-up by the stimulus. Instead, we argue that, following perceptual learning a specification of the diagnostic, object-based, SF information dynamically influences the top-down processing of retina-based SF information by these channels. Our analysis of SF processing provides a case study that emphasizes the continuity between higher-level cognition and lower-level perception.

Brain↗

PubMed1996

Personality and stress: an exploratory comparison of rheumatoid arthritis and osteoarthritis.

OBJECTIVE: To characterize and investigate the relationship between stress and personality in people with rheumatoid arthritis (RA) compared to those with osteoarthritis (OA). DESIGN: Survey of personality characteristics determined by using Cattell's 16 Personality Factor (16PF) questionnaire and stressful life events at disease onset determined by using the Social Readjustment Rating Scale of Holmes and Rahe. SETTING: Inpatients of an arthritis hospital and outpatients of a clinic, both of which specialize in rheumatic diseases and musculoskeletal problems. PARTICIPANTS: Diagnosed as "definite" or "classical" RA (N = 128) according to the ARA Diagnostic Criteria for Rheumatoid Arthritis (1958 Revision) or as OA (N = 79) according to radiological and clinical evidence; randomly selected, resulting in a close match for gender, age at disease onset, duration of disease, functional classification, and pattern of disease progress. All individuals approached participated. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Twenty personality characteristics, as well as amount of stressful life events at disease onset (Life Change Units). RESULTS: The RA subjects had significantly (p < .001) more stress at disease onset compared to the OA subjects. A subgroup of high-stress-at-onset RA subjects experienced a higher degree of disease severity (p < .01) than did the RA subjects with no stress at onset. Although the mean personality scores for those with RA were not significantly different from those with OA, the RA personality frequency distributions were different. Some of these differences could be explained by the stress-at-onset subgroup personality characteristics. CONCLUSIONS: As a group, subjects with RA exhibited more stress at disease onset than those with OA. Although mean personality scores were not different between RA and OA subjects, they did exhibit different frequency distributions. There appeared to be a high-stress-at-onset subgroup of RA patients who had a worse disease prognosis and who corresponded to a personality frequency subgroup. The interaction between these variables is more complex than implied by the "RA personality" concept.

Arthritis, Rheumatoid↗

PubMed1984

Block of avian cardiac fast sodium channels by tetrodotoxin is enhanced by repetitive depolarization but not by steady depolarization.

The blockade of Na+ channels by tetrodotoxin (TTX) was studied in the avian heart with the maximum rate of rise (Vmax) of phase 0 of the action potential used as an indicator of Na+ conductance (gNa). Inhibition by TTX of Vmax occurred at lower concentrations (IC50 congruent to 20 nM) than those reported in mammalian hearts (IC50, 1 to 10 microM). The IC50 was not affected by K+-induced membrane depolarization. Inhibition of closed Na+ channels by TTX was demonstrated and the degree of inhibition was increased by repetitive excitation. The time constant for recovery (tau Rec) from inactivation of Vmax was increased by TTX, a result consistent with the ability of the toxin to trap Na+ channels in the inactivated state. Reduction of the external Na+ concentration [( Na+]0 by 50% reduced the IC50 5.3-fold. This shift can largely be accounted for by the non-linear relationship between Vmax and gNa, that is, there need not be an important effect of [Na+]0 on toxin binding to its receptor. The interaction between TTX and its receptor in the avian heart is about as sensitive as that observed in peripheral nerve. However, like its less-sensitive mammalian heart counterpart, the TTX-Na+ channel interaction is frequency-dependent and apparently little influenced by membrane voltage or [Na+]0.

Animals↗

PubMed1997

The effects of mixing on behavior and circadian parameters of salivary cortisol in pigs.

The present study describes an experiment that was carried out to study the effects of mixing pigs once at 25 kg, preceded by transportation for 1.5 h, on the behavior and the circadian rhythmicity of salivary cortisol. The frequency of agonistic interactions was higher for mixed pigs. This was not only the case immediately after mixing, when pigs started to fight to establish a new social rank (p < 0.05), but also 5 to 6 weeks later; still more headknocks and bites towards other pigs were seen at that time among mixed pigs (p < 0.01). However, neither the basal cortisol concentration, assessed as the MESOR of the circadian rhythm of salivary cortisol, nor the amplitude of that rhythm was different between the groups.

Aggression↗

PubMed2003

Autonomic control of protein production by the parotid gland of the sheep.

The role of adrenoceptors in the control of parotid salivary function has been investigated in anaesthetized sheep. The enhancement of parotid protein output that occurs when the parasympathetic and sympathetic innervations to the gland are stimulated simultaneously in bursts at a low frequency (20 Hz for 1 s at 10-s intervals) was effectively abolished by pretreatment with propranolol (> or = 1.0 mg kg(-1), i.v., P < 0.001), without a comparable reduction in the flow of saliva or in the output of sodium or potassium. Secretion of protein was similarly augmented by simultaneous stimulation of the sympathetic innervation and an intracarotid infusion of acetylcholine (0.4-0.6 microg min(-1) g gland(-1)). This effect was also abolished by pretreatment with propranolol. Pretreatment with phentolamine (>1.0 mg kg(-1), i.v.) had no effect on the output of protein that occurred during combined stimulation of the parasympathetic and sympathetic innervations but increased the flow of saliva and the output of electrolytes. Stimulation of the parasympathetic innervation to the parotid gland caused a substantial fall in vascular resistance, which was reduced by the administration of atropine (0.5 mg kg(-1)). Stimulation of the sympathetic innervation caused a substantial rise in parotid vascular resistance in atropinized sheep. This effect was greater during continuous stimulation than during intermittent stimulation and enhanced by pretreatment with propranolol. It was virtually eliminated by pretreatment with phentolamine. It is concluded that the enhancement of protein output from the ovine parotid gland, that occurs during combined stimulation of the parasympathetic and sympathetic innervations at relatively low frequencies, depends upon interaction between cholinergic muscarinic and beta-adrenergic receptors. The vasoconstriction that occurs during sympathetic stimulation alone can be accounted for by activation of alpha-adrenoceptors.

Acetylcholine↗

PubMed1990

Resonance Raman spectroscopy of cytochrome c peroxidase single crystals on a variable-temperature microscope stage.

Good quality resonance Raman (RR) spectra have been obtained for cytochrome c peroxidase single crystals (0.2 x 0.5 x 1 mm) lying on their 110 faces on a microscope stage. Crystal orientation and polarization effects are observed which differentiate the RR bands on the basis of the symmetries of the porphyrin vibrational modes. The measured depolarization ratios are accurately calibrated for isolated bands of both totally symmetric and non totally symmetric modes by using a model of D4h chromophores in an oriented gas using the crystal structure atomic coordinates. The calculations indicate that the electronic transition moments are approximately along the lines connecting the methine bridges, suggesting an electronic steering effect of the vinyl groups. Deviations are observed for bands associated with the porphyrin v10 and the vinyl C = C stretching modes, which may be due to their near-resonant interaction. The band frequencies correspond to those of a five-coordinate high-spin FeIII heme, as previously observed in solution, consistent with the X-ray structure showing the Fe atom to be out of the heme plane on the proximal side with a distal water molecule located at a nonbonded distance, 2.4 A. The temperature dependence of the RR spectrum was determined with a Joule-Thompson cryostat on crystals sealed in glass capillaries. As the temperature is lowered, the spectrum converts to one characteristic of a low-spin FeIII heme. The conversion, which is readily reversible, is quite gradual. It is detectable at -50 degrees C but is incomplete even at -190 degrees C. A temperature effect on the protein structure is proposed which permits the Fe atom to approach the heme plane and bind the distal water molecule, or the distal histidine.

Cytochrome-c Peroxidase↗

PubMedDate not supplied

Microscopy of DNA in dilute polymer solutions.

The mechanism of separation of DNA in polymer solutions is not well understood. In this paper we use epifluorescence videomicroscopy to investigate the dynamic behavior of DNA electrophoresing through dilute polymer solutions. DNA collides with polymer obstacles, which cause the conformation of DNA to change from the globular, random coil conformation it takes in free solution. There are two main types of DNA-polymer collisions: U-shape collisions and brief collisions. In U-shape collisions, the DNA collides with a polymer obstacle, extends into a U-shape, and then slides around the polymer obstacle like a pulley. There are occasionally multiple entanglement points, causing the DNA to take more complex conformations, such as W-shapes. In the brief collision process, the DNA collides with a polymer obstacle and begins to extend but then collapses back into its globular conformation before a full U-shape is formed. The frequency of these interactions increases as the DNA size increases, and it also increases when the polymer size or concentration increases. These data support the transient entanglement coupling mechanism of separation of DNA, which states that entanglements between DNA and polymer molecules result in the separation of DNA.

Biotechnology↗

PubMed2004

Interpolyelectrolyte complexes of conjugated copolymers and DNA: platforms for multicolor biosensors.

Interchain interactions modulate the frequency of emission from a cationic water-soluble conjugated polymer. The polymer, PFPB, is obtained by a Suzuki copolymerization of p-phenylenebisboronic acid with a 95:5 mixture of 2,7-dibromo-9,9-bis(6'-bromohexyl)fluorene and 4,7-dibromo-2,1,3-benzothiadiazole, followed by quarternization of the pendant groups by addition of NMe3. The structure of PFPB contains 5% of the 2,1,3-benzothiadiazole (BT) chromophore within a cationic poly(fluorene-co-phenylene) polymer chain. The emission of PFPB is blue under dilute conditions (<1 x 10-6 M in repeat units) and green at higher concentrations. Energy transfer to dye-labeled ss-DNA is more efficient, relative to the parent polymer poly(9,9-bis(6'-N,N,N,-trimethylammonium)hexyl)fluorene-co-alt-1,4-phenylene) dibromide (PFP), as a result of improved spectral overlap. By using a peptide nucleic acid (PNA-C*) labeled with a red-emitting chromophore one can obtain three different emission colors, depending on the nature of the substrate under interrogation. If no ss-DNA is present, the solution emits blue. With a ss-DNA that is noncomplementary to PNA-C*, green emission is observed. Red emission occurs upon addition of ss-DNA complementary to the PNA sequence.

Biosensing Techniques↗

PubMed2001

The validity of proxy-based data in suicide research: a study of patients 50 years of age and older who attempted suicide. II. Life events, social support and suicidal behavior.

OBJECTIVE: To investigate the validity of proxy respondent reports of stressful life events, social support and suicidal behavior among individuals who attempted suicide. METHOD: Subjects were 80 psychiatric in-patients admitted following a suicide attempt. Data based on structured interviews with proxy respondents were compared with data based on interviews with subjects (gold standard). RESULTS: Specificity was higher than sensitivity across life event categories, and agreement was substantial for public and observable events (e.g. parent's death) but lower for more ambiguous events. Proxies were good judges of subject reports of frequency of social interaction but not perceived emotional support. Proxies were good judges of past history of suicide attempts and level of suicidal intent. CONCLUSION: Results support proxy-based data on suicidal behavior and certain aspects of social support and stressful life events in research of suicidal behavior in this age group, with potential implications for interpreting postmortem research of completed suicide.

Aged↗