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PubMed1998

Caffeine-induced arousal modulates somatomotor and autonomic differential classical conditioning in humans.

Two experiments (n = 48 and n = 45) investigated the effects of caffeine-induced arousal on differential classical conditioning of eyeblink (experiment 1) and autonomic (experiment 2) responses. Three groups of human subjects received double-blind administration of 0, 2, and 4 mg/kg oral caffeine (groups 0, 2, and 4, respectively). Twenty minutes after caffeine administration, a differential classical conditioning procedure was in effect. Physiological and subjective arousal was assessed by readings of blood pressure, skin conductance level, and a questionnaire, administered before caffeine administration, and after the conditioning procedure. The results showed increased indexes of physiological arousal in groups 2 and 4. In experiment 1, differential classical eyeblink conditioning was observed in groups 0 and 4, whereas no differential conditioning was seen in group 2. In experiment 2, differential classical conditioning was seen in group 0, whereas caffeine-induced arousal masked acquisition of conditioned skin conductance responses in group 4. This group displayed increased resistance to extinction compared to the other groups. Group 2, which had an intermediate level of arousal, did not display differential conditioning in either experiment. Taken together, the results indicate that small increases in arousal may be detrimental to learning, and larger increases in arousal may reverse this effect.

Adult↗

PubMed2002

Analysis of the entire genomes of thirteen TT virus variants classifiable into the fourth and fifth genetic groups, isolated from viremic infants.

TT virus (TTV) DNA in serum samples obtained from 24 TTV-infected infants was amplified by polymerase chain reaction (PCR) with inverse primers derived from the untranslated region. The amplified PCR products were molecularly cloned; six clones each were analyzed. Seventy-six (53%) of the 144 TTV clones were classified into group 4 (YONBAN isolates), and 22 (15%) into a novel genetic group (group 5). The TTV clones in group 4 were classified into 9 types, and those in group 5 into 4 types. The entire nucleotide sequence of one representative clone each from the 13 types were determined; they comprised 3570-3770 nucleotides, and had poor homology to TTVs of groups 1-3 (TA278, PMV and SANBAN isolates). A phylogenetic tree based on the entire nucleotide sequence of open reading frame 1 confirmed the presence of five distinct clusters separated by a bootstrap value of 100%. Analysis of 13 TTV variants demonstrated preservation of the genomic organization and transcription profile in all TTV groups. TTV group 4 was detected in 54% or 72% of 7-to-12-month-old infants in Japan and China, respectively, which is comparable with that among adults in the respective country, indicating early and frequent acquisition of this TTV group in infancy.

Adult↗

PubMedDate not supplied

A case of amnesia at an early age.

A dissociation between short- and long-term memory (LTM) and between the episodic and the semantic component of LTM is reported in a young girl who became amnesic at the age of 6 after an episode of acute encephalopathy resulting in bilateral frontal, insular, thalamic, ponto-mesencephalic, hippocampal and temporal lesions, as documented by MRI. The girl became amnesic a few months after starting school. A follow-up investigation showed that she was able to learn to read, write and acquire number facts and procedures and to improve her semantic knowledge. Our results show that the features of adult amnesia can also be found in children and that new semantic knowledge can be acquired in spite of an anterograde memory deficit. This dissociation does not agree with theories viewing long-term declarative memory as a unitary process mediated by the hippocampal system, but supports recent hypotheses that the acquisition of semantic knowledge is independent from episodic memory processes, and takes place through spared cortical regions subjacent to the hippocampi (Vargha-Khadem et al., 1997).

Amnesia↗

PubMed1999

Comparison of four magnetic resonance methods for mapping small temperature changes.

Non-invasive detection of small temperature changes (< 1 degree C) is pivotal to the further advance of regional hyperthermia as a treatment modality for deep-seated tumours. Magnetic resonance (MR) thermography methods are considered to be a promising approach. Four methods exploiting temperature-dependent parameters were evaluated in phantom experiments. The investigated temperature indicators were spin-lattice relaxation time T1, diffusion coefficient D, shift of water proton resonance frequency (water PRF) and resonance frequency shift of the methoxy group of the praseodymium complex (Pr probe). The respective pulse sequences employed to detect temperature-dependent signal changes were the multiple readout single inversion recovery (T One by Multiple Read Out Pulses; TOMROP), the pulsed gradient spin echo (PGSE), the fast low-angle shot (FLASH) with phase difference reconstruction, and the classical chemical shift imaging (CSI). Applying these sequences, experiments were performed in two separate and consecutive steps. In the first step, calibration curves were recorded for all four methods. In the second step, applying these calibration data, maps of temperature changes were generated and verified. With the equal total acquisition time of approximately 4 min for all four methods, the uncertainties of temperature changes derived from the calibration curves were less than 1 degree C (Pr probe 0.11 degrees C, water PRF 0.22 degrees C, D 0.48 degrees C and T1 0.93 degrees C). The corresponding maps of temperature changes exhibited slightly higher errors but still in the range or less than 1 degree C (0.97 degrees C, 0.41 degrees C, 0.70 degrees C, 1.06 degrees C respectively). The calibration results indicate the Pr probe method to be most sensitive and accurate. However, this advantage could only be partially transferred to the thermographic maps because of the coarse 16 x 16 matrix of the classical CSI sequence. Therefore, at present the water PRF method appears to be most suitable for MR monitoring of small temperature changes during hyperthermia treatment.

Body Temperature↗

PubMed1992

Effects of community-based, videotape, and flash card instruction of community-referenced sight words on students with mental retardation.

Community-referenced sight words and phrases were taught to adolescents with mild and moderate mental retardation using three instructional methods in two locations. Words were presented on flash cards in a school setting, on videotape recordings in a school setting, and on naturally occurring signs in the community. During each session, participants were taught one third of the words in each of these conditions and were then tested at the community sites. A constant prompt delay procedure was used to promote stimulus control to the experimenter's cue initially and then to transfer control to the textual stimuli used for training. A multiple baseline across participants design was employed. Results showed rapid acquisition of the community-referenced sight words in all three training conditions and generalization from the flash card and videotape conditions to the community sites.

Adolescent↗

PubMed1999

Post-termination ribosome interactions with the 5'UTR modulate yeast mRNA stability.

A novel form of post-transcriptional control is described. The 5' untranslated region (5'UTR) of the Saccharomyces cerevisiae gene encoding the AP1-like transcription factor Yap2 contains two upstream open reading frames (uORF1 and uORF2). The YAP2-type of uORF functions as a cis-acting element that attenuates gene expression at the level of mRNA turnover via termination-dependent decay. Release of post-termination ribosomes from the YAP2 5'UTR causes accelerated decay which is largely independent of the termination modulator gene UPF1. Both of the YAP2 uORFs contribute to the destabilization effect. A G/C-rich stop codon context, which seems to promote ribosome release, allows an uORF to act as a transferable 5'UTR-destabilizing element. Moreover, termination-dependent destabilization is potentiated by stable secondary structure 3' of the uORF stop codon. The potentiation of uORF-mediated destabilization is eliminated if the secondary structure is located further downstream of the uORF, and is also influenced by a modulatory mechanism involving eIF2. Destabilization is therefore linked to the kinetics of acquisition of reinitiation-competence by post-termination ribosomes in the 5'UTR. Our data explain the destabilizing properties of YAP2-type uORFs and also support a more general model for the mode of action of other known uORFs, such as those in the GCN4 mRNA.

5' Untranslated Regions↗

PubMed1987

Acquisition and analysis of fast single channel kinetic data on an Apple IIe microcomputer.

We describe a method for acquisition and analysis of single channel kinetic data, that uses a ubiquitous microcomputer, the Apple IIe (and is thus cheap), and is yet sensitive and powerful (analysis of up to 6000 events per run of the program; event detection only limited by the amplifier bandwidth). For data acquisition, the original record is converted into an idealized record of open and closed times, using half amplitude threshold analysis or a two-cursor window discriminator. A Time Interval Meter (TIM) has been developed that measures the durations of the TTL-signal from the window discriminator and stores up to 256 intervals in a FIFO-buffer. Each cycle of the TIM is completed within 1 microsecond. The, largely Pascal, software reads the intervals from the FIFO-buffer and stores them in the main memory of the microcomputer (cycle time 70 microseconds). The package is completed with Pascal programs for statistical analysis, including histogram construction of open and closed times, non-linear fit of up to 3 exponentials and correlation analysis.

Computers↗

PubMed2006

Time-resolved MR angiography with generalized autocalibrating partially parallel acquisition and time-resolved echo-sharing angiographic technique for hemodialysis arteriovenous fistulas and grafts.

PURPOSE: To evaluate the imaging of hemodialysis arteriovenous (AV) fistulas and grafts with use of magnetic resonance (MR) angiography with generalized autocalibrating partially parallel acquisition (GRAPPA) and time-resolved echo-sharing angiographic technique (TREAT) and compare the findings with those of digital subtraction angiography (DSA). MATERIALS AND METHODS: The vascular tree directly related to AV fistulas and grafts was divided into nine segments. Images of each segment obtained on GRAPPA MR angiography were evaluated for the presence of stenosis, occlusion, and any other disease (eg, pseudoaneurysm) by two independent observers and compared with a consensus reading of the same segments on DSA imaging. Sensitivity and specificity were calculated with use of DSA as the gold standard modality, and each image on MR angiography and DSA was rated for quality. Linear-weighted kappa scores were calculated as a measure of interobserver variability in the detection of pathologic processes. RESULTS: A total of 80 segments were evaluated by each observer. For both observers, sensitivity rates for the detection of stenosis, occlusion, and any disease were 100% (95% CI, 52%-100%), 100% (95% CI, 20%-100%), and 100% (95% CI, 60%-100%), respectively. For observer 1, specificity rates for the detection of stenosis, occlusion, and any disease were 96% (95% CI, 88%-99%), 100% (95% CI, 94%-100%), and 96% (95% CI, 88%-99%), respectively. For observer 2, the specificity rates for the detection of stenosis, occlusion, and any disease were 93% (95% CI, 84%-98%), 100% (95% CI, 94%-100%), and 93% (95% CI, 84%-97%), respectively. Linear-weighted kappa values for MR angiography and DSA were 0.78+/-0.084 and 0.62+/-0.152, respectively. CONCLUSION: Time-resolved MR angiography with GRAPPA and TREAT offers excellent image quality and provides an accurate and reliable modality for the detection of pathologic processes in hemodialysis AV fistulas and grafts.

Adult↗

PubMed2005

Schizophrenia and second language acquisition.

Language acquisition involves brain processes that can be affected by lesions or dysfunctions in several brain systems and second language acquisition may depend on different brain substrates than first language acquisition in childhood. A total of 16 Russian immigrants to Israel, 8 diagnosed schizophrenics and 8 healthy immigrants, were compared. The primary data for this study were collected via sociolinguistic interviews. The two groups use language and learn language in very much the same way. Only exophoric reference and blocking revealed meaningful differences between the schizophrenics and healthy counterparts. This does not mean of course that schizophrenia does not induce language abnormalities. Our study focuses on those aspects of language that are typically difficult to acquire in second language acquisition. Despite the cognitive compromises in schizophrenia and the manifest atypicalities in language of speakers with schizophrenia, the process of acquiring a second language seems relatively unaffected by schizophrenia.

Adult↗

PubMed1999

Acquisition of new capsular genes among clinical isolates of antibiotic-resistant Streptococcus pneumoniae.

Antibiotic-resistant clones of Streptococcus pneumoniae are recognizable through a combination of unique molecular, microbiological, and serological properties. In the course of surveillance of epidemic clones of S. pneumoniae, several isolates were identified that shared the clone-specific pulsed-field gel electrophoretic (PFGE) pattern and antibiotype but expressed serotypes atypical for the particular clone. A selected group of isolates belonging to the Spanish/USA clone but expressing serotypes 19, 14, or 3, instead of the expected serotype 23F, were tested using DNA probes for each of the 18 open reading frames (ORFs) of the 23F capsular locus. In no case were there any 23F-specific genes retained, with the possible exception of genes already known to be common to the capsular loci involved. Analysis of the sequence of the capsular locus of a penicillin-resistant serotype 23F isolate from Mexico showed that part of the cpsA gene of this strain, as well as genes cpsQ and cpsR, had high degrees of identity to the sequence of the homologous genes in isolates expressing serotype 19F. The capsular locus of this Mexican strain may have originated from an in vivo capsular switch event in which the original 19F locus was replaced by 23F-specific capsular genes.

Base Sequence↗

PubMed1988

Validity of sexual histories in a prospective study of male sexual contacts of men with AIDS or an AIDS-related condition.

As part of a prospective study in Toronto, Canada of male sexual contacts of men with either acquired immunodeficiency syndrome (AIDS) or an AIDS-related condition (primary cases), separate interviews were conducted in 1984-1985 with primary cases and their corresponding sexual contacts. Seventy-five primary cases and their corresponding sexual contacts were asked details concerning the sexual activities involved in their sexual encounters. Spearman correlation coefficients were calculated for the responses regarding frequency of various sexual activities between the primary case and his corresponding contact. Comparison of responses revealed good to excellent correlations for the majority of the sexual activities. Regression analysis of responses (dependent variable = contact's response; independent variable = primary's response) revealed the tendency for primary cases to report greater numbers of various activities than sexual contacts, as illustrated by regression coefficients that were consistently less than unity. Agreement between primary responses and sexual contact responses appeared to be affected by the time lapsed from the last sexual encounter with the contact and the date of the primary case's interview. No effect on agreement was observed when primary case diagnosis and the total number of other sexual partners of primary cases were considered. The authors conclude that such data can be captured with sufficient reliability and validity for use in epidemiologic investigations to assess the risk of acquisition of human immunodeficiency virus for the more common forms of sexual activity. However, some caution may be necessary in interpreting the results for some activities (anal digit insertion, anilingus) since agreement is less satisfactory for these activities.

AIDS-Related Complex↗

PubMed1987

Digitizing and signal averaging of left ventricular pressure signals using a dedicated radionuclide imaging system.

A method for obtaining left ventricular (LV) volume curves, synchronized with average LV pressure (LVP) curves for calculation of LV contractility, is described. Multiple gated blood pool imaging was performed to calculate average LV volume curves. Simultaneously with this acquisition, LVPs and aortic pressures were measured by indwelling catheters and recorded on an FM tape recorder. These signals were fed to the computer as image information and averaged and processed by the software developed for this purpose. Pressure resolution of the calibrated images was 4 mmHg/pixel when provision was made for a maximum pressure of 200 mmHg. A good correlation (r = 0.99) was obtained between the calculated peak LVPs and mean peak LVPs read from the chart recorder. The regression equation was: digitized peak LVP = 1.04 x chart recording--5.11 mmHg and the standard error of the estimate was 2.9 mmHg. Similar results were obtained with the aortic pressure (AP) measurements (digitized AP = 0.94 x chart recording + 6.37 mmHg, the standard error of the estimate was 3.8 mmHg). The digitized data also allowed the construction of pressure-volume loops for interpretation of ventricular contractility.

Animals↗

PubMed2004

An improved thin-layer chromatography/mass spectrometry coupling using a surface sampling probe electrospray ion trap system.

A combined surface sampling probe/electrospray emitter coupled with an ion trap mass spectrometer was used for the direct read out of unmodified reversed-phase C18 thin-layer chromatography (TLC) plates. The operation of the surface sampling electrospray ionization interface in positive and negative ionization modes was demonstrated through the direct analysis of TLC plates on which a commercial test mix comprised of four dye compounds viz., rhodamine B, fluorescein, naphthol blue black, and fast green FCF, and an extract of the caffeine-containing plant Ilex vomitoria, were spotted and developed. Acquisition of full-scan mass spectra and automated collection of MS/MS product ion spectra while scanning a development lane along the surface of a TLC plate demonstrated the advantages of using an ion trap in this combination. Details of the sampling system, benefits of analyzing a developed lane in both positive ion and negative ion modes, levels of detection while surface scanning, surface scan speed effects, and the utility of three-dimensional data display, are also discussed.

Amido Black↗

PubMed1987

Memory impairment associated with progression of Huntington's disease.

Huntington's Disease (HD) has been described as one example of a "subcortical" dementia, characterized by slowed cognitive processing and impairment of memory. We examined the relationship between slowed cognitive processing and memory impairment as a function of disease progression in patients with HD. Results from three experiments suggest that in the early stages of HD there is slowed cognition with intact memory acquisition and retrieval processes. In later stages, cognition is further slowed and specific impairments of memory become evident. Thus, memory impairment in HD would appear to change qualitatively with progression of the disease.

Adult↗

PubMed2002

Recursive retrospective revaluation of causal judgments.

Recursive causal evaluation is an iterative process in which the evaluation of a target cause, T, is based on the outcome of the evaluation of another cause, C, the evaluation of which itself depends on the evaluation of a 3rd cause, D. Retrospective revaluation consists of backward processing of information as indicated by the fact that the evaluation of T is influenced by subsequent information that is not concerned with T directly. Two experiments demonstrate recursive retrospective revaluation with contingency information presented in list format as well as with trial-by-trial acquisition. Existing associative models are unable to predict the results. The model of recursive causal disambiguation that conceptualizes the revaluation as a recursive process of disambiguation predicts the pattern of results correctly.

Adult↗

PubMed1998

Functional imaging by I0- and T2*-parameter mapping using multi-image EPI.

A new functional imaging method has been developed and used to measure T2*- and initial intensity (I0)-parameter maps of multiple slices during activation of the cortex with high temporal resolution. Multiple echo-planar images (EPIs) are read out after a single excitation of the spin system, leading to several images with increasing effective echo times. Changes induced by primary visual stimulation in T2* and I0 were measured in eight subjects. Although stimulation-induced increases in I0 only occurred at short repetition times, T2* increased from 57.3 to 60.9 ms on average. The method combines the high stability of a single shot EPI experiment with the high information content of a multiecho acquisition. In addition, stimulation-induced changes in inflow can be easily separated from true blood oxygenation level dependent (BOLD) signal changes.

Arousal↗

PubMed1997

Digital radiology using active matrix readout of amorphous selenium: construction and evaluation of a prototype real-time detector.

The goal of the present work is to develop a large area, flat-panel solid-state detector for both digital radiography and fluoroscopy. The proposed detector employs a photoconductive layer of amorphous selenium (a-Se) to convert x rays into charge. The charge image formed by the a-Se layer is electronically read out in situ using a two dimensional array of thin film transistors (TFTs), or active matrix. Since the active matrix readout is capable of producing x-ray images in real-time, it can potentially be applied in both radiography and fluoroscopy. In this paper, the imaging performance of this concept is investigated using a prototype x-ray imaging detector. The designs for the active matrix, the peripheral electronic circuits, and the image acquisition system are described. Measurements of x-ray imaging properties of the prototype detector, i.e., x-ray sensitivity, presampling modulation transfer function (MTF), and noise power spectrum (NPS), were performed, and from which the spatial frequency dependent detective quantum efficiency (DQE) of the prototype was derived. The experimental results are in agreement with the results of our theoretical analysis. The factors affecting the imaging performance and methods of improvement in the future are discussed.

Fluoroscopy↗

PubMed1993

Reproducibility of topometric data acquisition in normal and glaucomatous optic nerve heads with the laser tomographic scanner.

The reproducibility of optic disc cup measurements was analyzed in 24 eyes of 24 patients [8 normals, 8 glaucoma patients, 8 glaucoma suspects] using the Laser Tomographic Scanner. The mean coefficient of variation in triple measurements was 5.0% for the cup area, 5.4% for the rim area, 7.0% for the cup volume, 4.0% for the mean cup depth, and 4.3% for the maximum cup depth. Mean reliability between two of the three measurements performed in each eye was better than 0.988 for the cup area, 0.995 for the cup volume and 0.996 for the mean cup depth readings. These results suggest that laser scanning tomography allows highly reproducible measurements in living eyes and adds an important tool to the ophthalmologist's armamentarium for the diagnosis and follow-up of glaucoma patients.

Female↗