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Biomedical subjects

C Price

Publications and source records attributed to C Price.

At least 37 records · Page 2Linked to original sources
PubMed1994

A PET study of cognitive strategies in normal subjects during language tasks. Influence of phonetic ambiguity and sequence processing on phoneme monitoring.

We previously demonstrated using PET in normal subjects (Démonet et al., Brain 1992; 115: 1753-68) that, by comparison to a reference task of monitoring for pure tones, a phoneme monitoring task involving two factors of complexity (sequence processing and perceptual ambiguity) activated Wernicke's area and Broca's area. In the present experiment, we explored the respective influence of these factors on brain activation. In addition to the reference task, four phoneme monitoring tasks in non-words were used with stimuli presented binaurally. These included an easy, non-sequential, unambiguous task; a perceptually ambiguous, but non-sequential task; a sequential, but perceptually unambiguous task; a sequential and ambiguous task identical to the one we used in our previous study. Changes in regional cerebral blood flow were measured in nine right-handed volunteers using PET and infusion of H2(15)O. The sequential unambiguous task was associated with the same pattern of activation as that observed for the equivalent non-sequential task, i.e. activation of Wernicke's area. The two tasks with perceptual ambiguity gave rise to activations in the left fusiform gyrus and in Broca's area, respectively. Activation of the left fusiform gyrus in the perceptually ambiguous but non-sequential task suggests a prominent role for a strategy involving phoneme-to-grapheme transcoding in subjects, who thereby attempted to visualize non-words that they could not decipher auditorily. Activation of Broca's area in the sequential and ambiguous task reproduces our previous result and suggests that subjects resorted to a predominantly verbal rehearsal strategy when performing this task.

Adult↗
PubMed1994

Embryonic fat-cell lineage in Drosophila melanogaster.

The Drosophila adipose tissue, or fat body, and the bodywall muscle are two major tissues derived from the mesoderm. Although much is known about the lineage of muscle cells, little is known about the development of the fat body. Using known genes and an enhancer trap (29D), we have begun to trace the lineage of the cells comprising the fat body. The genes Adh (alcohol dehydrogenase) and DCg1 (type IV collagen) code for gene products involved in fat-cell metabolism and therefore serve as terminal fat-cell differentiation markers. The expression of these genes was used to identify the fat body at stage 17 and to identify the start of terminal fat-cell differentiation at stage 15. We found that the steroid-hormone receptor gene, svp (seven-up), was expressed transiently within the fat-cell lineage from stages 12 to 14. We suggest that stage 12 marks the beginning of early fat-cell differentiation and that the svp-positive cells within the mesoderm are early precursor fat cells. To confirm the identity of these cells and to establish the role of svp in the developing fat cell, we examined svp mutant embryos for alterations in the expression of the two terminal fat-cell differentiation markers, Adh and DCg1. Loss of svp function resulted in the loss of Adh transcript and a reduction of DCg1 expression specifically in the fat body. Thus, svp plays a role in fat-body-specific expression of at least two terminal fat-cell differentiation genes. In contrast to svp, we found no evidence that the steroid receptor HNF-4(D) gene was expressed in the fat body nor that it was involved in the development of this tissue. Using an enhancer-trap line (29D), we further traced the fat-cell lineage to nine bilateral clusters of cells within the mesoderm at germ-band extension. We suggest these 29D-positive cells represent the progenitor fat cells. In stage-12 embryos, the 29D-positive cell clusters can be identified within the mesoderm internal to nautilus-expressing cells. These data suggest that the precursor fat cells may be derived from the inner mesoderm, or spanchnopleura. Embryos deficient for the DNA region surrounding the site of the 29D enhancer trap lack most, if not all, of the cells in the fat-cell lineage. These embryos exhibit the loss of svp-positive precursor fat cells and concomitant loss of fat-body-specific expression of Adh and DCg1.(ABSTRACT TRUNCATED AT 400 WORDS)

Alcohol Dehydrogenase↗
PubMed1994

Hunting-related spinal cord injuries among Oklahoma residents.

While major causes of traumatic spinal cord injuries have been described as motor vehicle crashes, falls, sports-related events, and injuries related to violence, causes of serious consequence but of lesser magnitude have not been widely reported. This report, drawn from Oklahoma State Department of Health spinal cord injury surveillance data, describes the incidence and circumstances surrounding hunting-related spinal cord injuries. All of the injuries resulted from falls from trees or tree stands. The incidence rate of injury was less than one per 100,000 licensed hunters. Half of the injuries resulted in neurological damage severe enough to result in permanent paralysis or death. The circumstances of the injuries suggest a need for educating hunters concerning safe hunting practices and safe tree stand use, including inspection of trees for weak or dead branches, and use of a safety belt when ascending, descending, or sitting in a tree or tree stand.

Accidental Falls↗
PubMed1993

Identification of a gene encoding a novel zinc finger protein in Saccharomyces cerevisiae.

In the course of a comprehensive genomic screen for cell cycle regulated genes in the yeast Saccharomyces cerevisiae (Price et al., 1991) we identified and characterized a transcriptional unit encoding a putative zinc finger protein named FZF1 (EMBL accession number: X67787). This gene encodes a protein containing five zinc fingers of the Cys2His2 class, three of which are positioned in tandem at the N-terminus. The fourth and fifth finger follow after an interruption of 61 and 66 amino acids, respectively. While FZF1 is constitutively expressed at a very low level, its deletion is not essential for growth. Its similarity with known transcription factors, however, suggests that the FZF1 gene product may serve as a transcription factor in yeast.

Amino Acid Sequence↗
PubMed1993

An evaluation of the Sens-A-Ray digital dental imaging system.

The Sens-A-Ray digital imaging system was compared with group D- and E-speed intraoral radiographic film with respect to resolution, speed and image quality. Using a line-pair plate, resolution was determined to be 10 line-pairs per millimetre. With a constant potential X-ray source, the speed of the system was over three times that of E-speed emulsion and the response of pixel value to exposure was linear. Absorption curves with aluminium showed a similar response to D-speed film. An aluminium foil test object was used to compare the Sens-A-Ray system with both film types. Thirty observers were scored for successful identification of a pattern of holes in the test object. There was little difference between D- and E-speed film groups, and successful identification was significantly reduced with the Sens-A-Ray images when compared with D- and E-speed films.

Evaluation Studies as Topic↗
PubMed1992

Euplotes crassus has genes encoding telomere-binding proteins and telomere-binding protein homologs.

We have identified two 1.6 kb macronuclear DNA molecules from Euplotes crassus that hybridize to the alpha subunit of the Oxytricha telomere protein. We have shown that one of these molecules encodes the 51 kDa Euplotes telomere protein while the other appears to encode a homolog of the telomere protein. Although this homolog clearly differs in sequence from the Euplotes telomere protein, the two proteins share extensive amino acid sequence identity with each other and with the alpha subunit of the Oxytricha telomere protein. In all three proteins 35-36% of the amino acids are identical, while 54-56% are similar. The most extended regions of sequence conservation map within the N-terminal section; this section has been shown to comprise the DNA-binding domain in the Euplotes telomere protein. Our findings suggest that some of the conserved amino acids may be involved in DNA recognition and binding. The gene encoding the telomere protein homolog contains two introns; one of these introns is only 24 bp in length. This is the smallest mRNA intron reported to date.

Amino Acid Sequence↗
PubMed1992

Regional response differences within the human auditory cortex when listening to words.

The relationship between activity within the human auditory cortices and the presentation rate of heard words was investigated by measuring changes in regional cerebral blood flow with positron emission tomography. We demonstrate that in the primary auditory cortices and middle regions of the superior temporal gyri there is a linear relationship between the rate of presentation of heard words and blood flow response. In contrast, the blood flow response in an area of the left posterior superior temporal gyrus (Wernicke's area) is primarily dependent on the occurrence of words irrespective of their rate of presentation. The primary auditory cortices are associated with the early processing of complex acoustic signals whereas Wernicke's area is associated with the comprehension of heard words. This study demonstrates for the first time that time dependent sensory signals (heard words) detected in the primary auditory cortices are transformed into a time invariant output which is channelled to a functionally specialised region--Wernicke's area. Wernicke's area is therefore distinguished from other areas of the auditory cortex by direct observation of signal transformation rather than by association with a specific behavioural task.

Adult↗
PubMed1992

The HsdS polypeptide of the type IC restriction enzyme EcoR124 is a sequence-specific DNA-binding protein.

The HsdS and HsdM polypeptides of the type IC restriction enzyme EcoR124 have been purified independently and used in a set of gel retardation experiments to determine the minimum requirements for sequence-specific recognition of DNA by this enzyme. The HsdS polypeptide alone is able to bind to DNA in a sequence-specific manner. In addition, whilst the presence of the HsdM polypeptide gives rise to a stimulation of DNA binding by the HsdS subunit it is not clear whether, under the conditions of the experiments reported here, the HsdS subunit maintains the same interactions with the HsdM subunits observed in the absence of DNA.

Bacterial Proteins↗
PubMed1992

Diagnosis of cytomegalovirus infection in heart transplant recipients.

In a prospective study eight (47%) heart transplant recipients had recurrent cytomegalovirus (CMV) infection. Of these, five had received hearts from seropositive donors. Neither serology nor virus isolation from urine was reliably associated with clinical CMV infection, but a high CMV IgM index correlated with CMV infection.

Antibodies, Viral↗
PubMed1992

Effects of niobium filtration and constant potential on image quality in dental radiography. 2. Objective assessment.

The effects of niobium filtration and constant potential on image quality were explored by asking observers to identify numbers of circular areas of small density differences in zones of high and low density. Successful identification was related negatively to half-value layer. This relationship was particularly strong in the case of self-rectified units without additional niobium filtration and the constant potential units (r2 = 0.994, P < 0.0005). Constant potential had no effect other than in relation to half-value layer. Additional niobium filtration detracted from successful identification, but slightly less than would be predicted by the half-value layer. Whether this difference is significant or relevant has not been established. The findings of this study, in conjunction with our previous investigations, have failed to demonstrate any clear indications for preferring constant potential supply over self-rectification or for using niobium as an additional filter material. Half-value layer has been shown to be a reliable indicator of the effects of beam quality on emulsion speed, attenuation in water, and image quality. It appears that the methods employed to change the beam quality have no specific effects.

Filtration↗
PubMed1992

Effects of additional filtration on image quality in dental radiography: comparison of niobium with aluminium.

Niobium filtration was compared with additional aluminium filtration with respect to the image quality of dental radiographs. An aluminium phantom was constructed which produced densities similar to those found in periapical regions and in enamel. Eight beam qualities were investigated and objective evaluation of the films was made by 20 observers with respect to any effects on radiographic contrast and successful identification of a pattern of holes in the phantom. Radiographic contrast decreased linearly as the half-value layer increased (r2 = 0.960, P < 0.0005), confirming the negative relationship between contrast and half-value layer as previously shown. No specific effect of niobium filtration on radiographic contrast was demonstrated. The number of successful identifications decreased with increasing half-value layer. A regression analysis in the total and dark zones yielded r2 values of 0.937 and 0.943 (P < 0.0005). Similar analyses for both the light and overall zones showed weaker relationships (r2 = 0.734 and 0.742: P = 0.007 and 0.006 respectively). Niobium reduces successful identification to the same extent as equivalent aluminium filtration.

Aluminum↗
PubMed1992

Three-dimensional reconstruction of magnetic resonance images of the temporomandibular joint by I-DEAS.

Evaluation of the temporomandibular joint has been limited by the inability of current technology to image complex morphology and motion in three dimensions. An engineering design program, I-DEAS, has been used to construct solid models from magnetic resonance images. A dried skull with an acrylic resin temporomandibular disc replica, immersed in water, provided sagittal and coronal MR images. Linear dimensions and disc volumes obtained from the models were compared with the original and found to be consistent, within the limits imposed by the slice thickness. We have applied the method to the living joint in an asymptomatic volunteer, and report our initial experience in demonstrating the spatial relationships and motion of the joint components.

Humans↗