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Biomedical subjects

D L King

Publications and source records attributed to D L King.

At least 19 recordsLinked to original sources
PubMed1992

DNA binding and heteromerization of the Drosophila transcription factor chorion factor 1/ultraspiracle.

The Drosophila chorion factor 1/ultraspiracle (CF1/USP) transcription factor, a homologue of the retinoid X receptor, is a developmentally important member of the family of nuclear (steroid) hormone receptors. Using newly developed monoclonal antibodies and a full-length bacterially produced protein, we have studied in detail the in vitro DNA-binding properties of this factor and aspects of its distribution in vivo. During oogenesis, CF1/USP is present both in germline cells and in the somatic follicular epithelium. We have determined the optimal binding site of partially purified bacterially produced CF1/USP by an in vitro selection procedure and also have characterized its binding to the follicular-specific chorion s15 promoter. In vitro this bacterially produced factor is unusual in binding to a single element ("half-site"); simultaneous but noncoordinate binding to a second half-site is possible if these repeated elements are organized in direct orientation and spaced adequately. However, the factor interacts synergistically with several other nuclear hormone receptors: notably, it can form in vitro heteromers with mammalian thyroid and retinoic acid receptors, binding to two half-sites that are organized in either direct or inverted orientation. In vivo the factor most probably functions as a heterodimer, but its partner(s) remains to be determined.

Animals↗
PubMed1992

Improved reproducibility of left atrial and left ventricular measurements by guided three-dimensional echocardiography.

OBJECTIVES: The objective of this study was to determine whether guided three-dimensional echocardiography could improve the reproducibility of left atrial and left ventricular anteroposterior measurements over that of standard unguided two-dimensional echocardiography. BACKGROUND: Although these measurements are standard indexes for evaluating chamber size, their use is limited by significant interobserver variability largely due to variable image plane positioning. To improve measurement accuracy and reproducibility, we have developed a three-dimensional echocardiograph that displays the line of intersection of the real-time image with a previously saved orthogonal reference image. This display shows the relation of the real-time image to anatomic landmarks in its third, nonvisualized dimension and may be used to guide image positioning. METHODS: Three pairs of operators independently performed unguided two-dimensional and guided three-dimensional examinations on three groups of 10 patients each. The left atrium was measured in a plane through the inferior surface of the aortic cusps and the left ventricle in a plane perpendicular to its long axis 1 cm below the mitral leaflet tips. Interobserver variability of these measurements on unguided parasternal long-axis images and on guided short-axis images was assessed. RESULTS: The standard unguided two-dimensional examination was associated with an interobserver variability of 14.6% and 9.1% for atrial and ventricular measurements, respectively. Guided three-dimensional echocardiography significantly reduced interobserver variability to 5.0% and 3.1%, respectively, for the same measurements (p < 0.005 by McNemar's test). CONCLUSIONS: Significant interobserver variability occurs with standard unguided two-dimensional echocardiographic measurement of left atrial and left ventricular dimensions. Guided three-dimensional echocardiography achieves a nearly threefold improvement of reproducibility of these measurements and provides the basis for improved serial evaluation and comparison of atrial and ventricular size by different operators.

Adult↗
PubMed1992

Amelioration of mitral valve prolapse after treatment for panic disorder.

Twenty panic disorder patients with mitral valve prolapse showed amelioration of prolapse on repeat echocardiogram after treatment for panic disorder. This effect was significant when compared to repeat echocardiograms in eight psychiatrically normal control subjects with mitral valve prolapse.

Adult↗
PubMed1991

The effect of the size of one and two traffic signs on two measures of perceptual performance.

A large object can delay the perception of a small object, which hints that the use of larger objects in general and larger traffic signs in particular may be counterproductive. The present study employed either one traffic sign or two contiguous traffic signs on a post in a photograph of a road scene. Identification of a small target sign was not slower when a second sign was contiguous than when there was only the one small target sign, regardless of whether the contiguous sign was large or small. Furthermore, when a counting task was used with the same stimuli, a large sign accelerated the response to two-sign stimuli, again regardless of the contiguous sign's size. In addition, the response to two-sign stimuli was not slower than the response to one-sign stimuli. The large small comparisons of both experiments reduce the concern that employing a large traffic sign will delay the perception of a second contiguous sign. Moreover, the one-two comparisons of both experiments imply that employing two contiguous signs will not delay the perception of a sign, despite widespread evidence that a nearby object will delay the perception of a target object.

Adult↗
PubMed1991

Evaluation of in vitro measurement accuracy of a three-dimensional ultrasound scanner.

We have constructed a three-dimensional (3-D) ultrasound scanner to make examinations easier and more accurate. The accuracy of the 3-D scanner has been determined by scanning a three-dimensional model. Lengths, angles, and volume of the model were computed and compared to values determined from physical measurement. Distances between image planes were computed with a mean error of 0.4% of true value. Volume was computed with a mean error of 1.6%, or 0.64 mL +/- 0.72 mL (1 SD). We conclude that the 3-D scanner has a system error of less than 0.4%, that it does not introduce significant new errors, and that the principal source of measurement error is poor lateral resolution due to ultrasound beam width. We believe that the 3-D scanner may be a clinically useful instrument for quantitative echographic measurements.

Algorithms↗
PubMed1990

The chorion genes of the medfly, Ceratitis capitata, I: Structural and regulatory conservation of the s36 gene relative to two Drosophila species.

We have used low stringency screening with the Drosophila melanogaster s36 chorion gene to recover its homologue from genomic and cDNA libraries of the medfly, Ceratitis capitata. The same gene has also been recovered from a genomic library of D. virilis. The medfly s36 gene shows similar developmental specificity as in Drosophila (early choriogenesis). It is also specifically amplified in ovarian follicles; this is the first report of chorion gene amplification outside the genus Drosophila. Alignments of s36 sequences from three species show that, in addition to its regulatory conservation, the s36 gene is extensively conserved in sequence, in a region corresponding to a central protein domain, and in short regions of 5' flanking DNA that might correspond to cis-regulatory elements.

Amino Acid Sequence↗
PubMed1990

Cardiac left ventricular hypertrophy and chamber dilatation in panic disorder patients: implications for idiopathic dilated cardiomyopathy.

Echocardiographic comparison of 35 panic disorder patients to 35 normal control subjects found subclinical increases of cardiac left ventricular chamber size in eight panic patients (and one control subject), and of left ventricular mass (corrected for body surface area) in seven panic patients. There was a significantly greater variance of left heart chamber size and corrected mass in panic patients compared with control subjects, without significant group mean differences. Consistent with a previously reported association of panic anxiety and idiopathic dilated cardiomyopathy, this study suggests that some healthy panic patients may have subclinical myocardial changes.

Adult↗
PubMed1990

Changes in the morphology of the buccal alveolar bone of protruded mandibular permanent incisors secondary to orthodontic alignment.

The cephalometric radiographs of 17 children and adolescents whose orthodontic treatment involved lingual positioning of procumbent mandibular central permanent incisors were examined to determine the morphologic changes in the buccal alveolar bone that resulted from orthodontic treatment. Comparison of tracings fom radiographs taken before and after treatment indicated that the alveolar height increased in 58.8% of the cases. In these cases a significant increase in the distance from the incisal edge to the "D" point was evident (t = 2.5, p less than or equal to 0.03), whereas this dimension decreased significantly in the rest of the cases (t = 3.0, p less than or equal to 0.02). In addition, a significant positive correlation (r = 0.95) was found between the changes in the distances from the "D" point to the incisal edge and the alveolar bone height. These findings indicate that during orthodontic treatment that involves lingual positioning of procumbent teeth but no intrusion, an increase in the amount of buccal alveolar bone may take place.

Adolescent↗
PubMed1990

Proteins that bind to Drosophila chorion cis-regulatory elements: a new C2H2 zinc finger protein and a C2C2 steroid receptor-like component.

Gel mobility-shift assays have been used to identify proteins that bind specifically to the promoter region of the Drosophila s15 chorion gene. These proteins are present in nuclear extracts of ovarian follicles, the tissue where s15 is expressed during development, and bind to specific elements of the promoter that have been shown by transformation analysis to be important for in vivo expression. The DNA binding specificity has been used for molecular cloning of two components from expression cDNA libraries and for their tentative identification with specific DNA-binding proteins of the nuclear extracts. The mRNAs for both of these components, CF1 and CF2, are differentially enriched in the follicles. DNA sequence analysis suggests that both CF1 and CF2 are novel Drosophila transcription factors. CF2 is a member of the C2H2 family of zinc finger proteins, whereas CF1 is a member of the family of steroid hormone receptors. The putative DNA-binding domain of CF1 is highly similar to the corresponding domains of certain vertebrate hormone receptors and recognizes a region of DNA with similar, hyphenated palindromic sequences. The nature of CF1 raises the possibility of hormonal control of choriogenesis in Drosophila.

Amino Acid Sequence↗
PubMed1990

A large rectangle delays the perception of a separate small rectangle.

Deciding whether two objects, rather than one, are present takes longer for large-small and small-large pairs of rectangles than for large-large and small-small pairs of rectangles. This large-small slowdown was eliminated when the large rectangle was slightly modified, when the large and small rectangles were contiguous, or when the task was to identify the large rectangle. However, it did occur when the task was to identify the small rectangle. These results suggest that the large rectangle delayed the perception of the small rectangle. Codes for features did not cause this delay. Instead, the evidence indicates that each rectangle evoked its own superordinate code, and that the large-rectangle superordinate code produced the gestalt of a large rectangle and also inhibited the small-rectangle superordinate code, thereby delaying the perception of the gestalt of a small rectangle. Thus, superordinate codes may also be the direct cause of other gestalts and their associated perceptual outcomes.

Adult↗
PubMed1990

Three-dimensional spatial registration and interactive display of position and orientation of real-time ultrasound images.

Ultrasound images may be difficult to interpret because of the lack of an image orientation display. To resolve this problem, a three-dimensional (3-D) ultrasound scanner has been constructed that provides spatial registration and display of position and orientation of real-time images while allowing unconstrained movement of the scanning transducer. It consists of a conventional sector scanner, a 3-D acoustical spatial locater, and a personal computer. It displays within each image the line of intersection of two image planes, a reference image, and a live image. This display guides and documents image positioning. The scanner's 3-D data also provide the potential for computergraphic modeling of organs, the ability to calculate volumes using nonparallel, nonintersecting image planes, and the capability for 3-D color flow mapping and measurement of Doppler angle.

Humans↗
PubMed1990

Gestalts are more closely associated with performance on a discrimination task than are component stimuli.

Distance, similarity, and other components of the physical stimulus but also gestalts are associated with the ability to discriminate between two objects. The present research bears on this confound. Identical lines were added to the opening and closing bracket of a pair of brackets to form two identical rectangles. A stimulus consisted of either one or two of these brackets, lines, or rectangles. Subjects indicated as quickly as possible whether one or two objects occurred. The discriminations between two near brackets and two near lines were more difficult than the discrimination between two near rectangles. A large distance between two objects improved the bracket and line discriminations more than the rectangle discrimination. Single brackets and lines did not result in poorer performance than did single rectangles. These results disconfirm the distance, similarity (including relational similarity), good continuation, location of geometric centers, size, closedness, symmetry, spatial frequency, redundancy, and number of lines component stimulus predictions at least twice. Both the two near brackets and the two near lines produce single gestalts, whereas each remaining 2-object stimulus results in two gestalts. Therefore, gestalts predicted performance better than did component stimuli. Another result was that the 2-object responses were faster than the 1-object responses for far objects.

Analysis of Variance↗
PubMed1989

Developmentally regulated alternative splicing of Drosophila integrin PS2 alpha transcripts.

We report the characterization of a chromosomal integrin gene that encodes the Drosophila PS2 alpha subunit. The gene is composed of 12 exons spanning 31 kb. By employing a novel method for directed cDNA cloning, we have analyzed over 300 independent cDNA clones for the existence of alternate RNA products. Two forms of PS2 alpha mRNA are frequently observed: a canonical (C) form and a form lacking the 75 nucleotide exon 8 (m8). The relative ratio of these two forms varies widely during development. Although region A, derived from exon 8 and the adjacent 25 amino acids, shows weak conservation among the sequences of alpha subunits that bind to different ligands, it is highly conserved in the homologous PS2 alpha gene of the distantly related Mediterranean fruitfly. We suggest that the variable region A may be important in determining the specificity and affinity of integrin receptors for their ligands.

Amino Acid Sequence↗
PubMed1989

A rapid sample-preparation technique for thin-layer chromatographic analysis for 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in human urine.

In this rapid TLC method of analysis for the urinary cannabinoid metabolite, 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), hydrolyzed urine specimens are aspirated through a porous, alkyl-silica extraction layer located along the lower edge of a biphasic thin-layer chromatogram; THC-COOH is simultaneously extracted from the sample and concentrated on the TLC plate for subsequent migration and detection. The method, evaluated in a blind study, identified all samples containing THC-COOH greater than or equal to 20 micrograms/L. The technique increases samples throughput, sensitivity, and specificity as compared with conventional TLC methods and is applicable to a wide variety of compounds.

Chromatography, Thin Layer↗
PubMed1989

ABO blood group incompatibility and primary tooth discoloration.

A case report of discolored anterior primary teeth is presented. Medical history and clinical findings suggest an etiology of hemolytic anemia and jaundice secondary to ABO blood group incompatibility. There are no previous reports of tooth discoloration resulting from ABO blood group incompatibility.

ABO Blood-Group System↗
PubMed1988

A ricin agglutinin-resistant clone of Leishmania donovani deficient in lipophosphoglycan.

A variant cell line of Leishmania donovani (named R2D2) has been selected for resistance to the cytotoxic lectin ricin agglutinin and shown to be defective in the synthesis of its major glycoconjugate lipophosphoglycan. Compared to the parental line, R2D2 cells showed a marked resistance to the toxic effects of ricin and an increased sensitivity toward concanavalin A. The synthesis of lipophosphoglycan by R2D2 cells was judged to be less than 1% relative to that of wildtype cells as determined by incorporation of radioactive mannose and galactose and by electrophoretic and chromatographic analyses. Although lacking lipophosphoglycan, R2D2 parasites were capable of infecting cultured U937 macrophages.

Animals↗
PubMed1988

Comparison of theoretical scattering results and ultrasonic data from clinical liver examinations.

A theoretical analysis of soft-tissue ultrasonic scattering has been used to formulate specific results describing spectral parameters for tissue characterization. Results are applicable to clinical liver examinations. Three spectral parameters are mathematically expressed in terms of acoustic attenuation and the effective sizes, concentrations, and relative acoustic impedances of tissue scatters. Results from a clinical data base are shown to agree well with analytical results for each spectral parameter. Agreement is found for: spectral shapes; effects of attenuation; and correlations between parameters. Images of three spectral parameters are presented and their gray-scale features are evaluated with reference to analytical results.

Humans↗