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B L Craine

Publications and source records attributed to B L Craine.

10 recordsLinked to original sources
PubMed1998

Digital imaging colposcopy: corrected area measurements using shape-from-shading.

The quantitative measurement of areas on the cervix is of interest to researchers studying the natural history of human papilloma viral lesions. Measurement of areas from images obtained through a colposcope are, however, inherently in error due to the image being a two-dimensional projection of a three-dimensional object. The ability to correct for these errors through use of digital imaging colposcopy and a practical application of a shape from shading algorithm was developed in this study. The shape from shading technique requires empirical measurement of the relationship between observed light intensity and the viewing angle (referred to as a reflection map). It was found that a population mean reflection map provided a correction that was about as accurate as using an individual's own reflection map (making it unnecessary to measure a map for each exam). Digital red filtering of the images increased accuracy and precision of measurement.

Adolescent↗
PubMed1993

Digital imaging colposcopy: basic concepts and applications.

The technique of colposcopy has changed little since the introduction of the green filter to improve viewing of vascular structures. However, the recent dramatic improvements in computer technology now make it practical to combine computerized image processing with colposcopy, which we have termed "digital imaging colposcopy." Image processing techniques permit contrast enhancement of features, such as white epithelium and abnormal vasculature. The digital colposcope allows rapid measurement of the cervical area involved with visible lesions, providing an improved means of following the progression of these lesions over time.

Colposcopy↗
PubMed1990

Computer-assisted analysis of transrectal ultrasound images.

We have developed a microcomputer based system with an application specific software package which permits the direct digitization and analysis of transrectal ultrasound (TRUS) images. The system is highly flexible and enables access to a wide range of image analysis tools through relatively simple software modifications, which cannot be implemented using a standard ultrasound instrument. We have demonstrated the capability of the system by an analysis of a number of morphometric parameters and by a correlation of these measurements with the presence of prostatic cancer. We found that the measurement of the ratio of the anterior-posterior axis to transverse axis and the presumed circular area ratio (PCAR) were significant predictors of prostatic cancer. The sensitivity of the PCAR measurement was 93%, the specificity was 50%, the positive predictive value was 57%, and the negative predictive value was 91%. The high negative predictive values of these parameters may provide objective criteria to allow for selective biopsy of patients. This system provides researchers with an efficient, economical, and flexible method to aid in the analysis of TRUS images in a quantitative manner.

Humans↗
PubMed1990

The computerized digital imaging colposcope: future directions.

A computer-aided colposcope has been developed for enhancement and analysis of colposcopic images. There are numerous possible applications of this system, including image archiving, image enhancement and processing, and quantitative measurements of various features in the images. In addition, a wide range of digital filters can be applied to the system that may be used to detail different aspects of the image. The method for a new mode of applying digital and optical filters to the colposcope is discussed and future directions for the system are suggested.

Colposcopes↗
PubMed1982

Novel selection for tetracycline- or chloramphenicol-sensitive Escherichia coli.

A method for selecting tetracycline- or chloramphenicol-sensitive Escherichia coli cells from a population of predominantly resistant cells is described. This method depends on the inability of drug-sensitive cells to induce lambda receptors in the presence of chloramphenicol or tetracycline, protein synthesis-inhibiting drugs. The addition of bacteriophage lambda vir to a mixture of drug-sensitive and drug-resistant cells, induced for lambda receptors in the presence of tetracycline or chloramphenicol, preferentially kills the drug-resistant cells (which are capable of inducing lambda receptors). The result is a culture enriched for the sensitive cells. Several common strains used for transformation were compared for their ability to be selected. E. coli 294 was found to be superior.

Cell Survival↗
PubMed1981

Transcription of the major Drosophila heat-shock genes in vitro.

Active eukaryotic genes are more accessible to some proteins than bind DNA than are inactive genes. In order to probe the accessibility of the Drosophila heat-shock genes we have isolated nuclei from Drosophila tissue culture cells and have used these nuclei as templates for Escherichia coli RNA polymerase. With nuclei isolated from cells that had not been heat shocked, the synthesis of heat-shock RNA was not detected by hybridization to a DNA clone containing sequences from the major heat-shock region. In contrast, approximately 0.22% of the RNA synthesized in nuclei isolated from cells that had been previously heat shocked hybridized to the heat-shock clone. The synthesis of heat-shock RNA was DNA dependent, was sensitive to rifampicin and to actinomycin D, and represented a 70-fold enrichment over random transcription of the Drosophila genome. Transcription showed an extraordinary preference for a region 5' distal to the structural gene. These results demonstrate that preferential transcription by the bacterial RNA polymerase is indicative of the active state of Drosophila genes.

Animals↗
PubMed1981

Activation of the major drosophila heat-shock genes in vitro.

Inactive Drosophila heat-shock genes of isolated diploid nuclei can be induced to a transcriptionally active state by exposure to cytoplasmic extracts from heat-shocked Drosophila cells. No effect was observed on histone gene transcription, and extracts from non-heat-shocked cells were ineffective. The factor in the cytoplasmic extract has been partially purified and characterized. It is protease-sensitive and heat-labile. A striking change accompanies in vitro activation that permits transcription by E. coli RNA polymerase of the chromatin 5' -distal to the structural genes at the 87A and 87C heat-shock gene loci; we have previously observed a similar change after in vivo heat-shock induction. That this change occurred in the absence of endogenous RNA polymerase II activity suggests that these changes may reflect the earliest event in gene activation. Inasmuch as activation also took place after histone H1 depletion, this histone does not appear to be essential for this step of gene activation.

Animals↗
PubMed1979

Deoxyribonucleic acid-membrane interactions near the origin of replication and initiation of deoxyribonucleic acid synthesis in Escherichia coli.

A previously reported salt-sensitive binding of deoxyribonucleic acid (DNA) to the cell envelope in Escherichia coli, involving approximately one site per chromosome near the origin of DNA replication, is rapidly disrupted in vivo by rifampin or chloramphenicol treatment and by amino acid starvation. DNA replication still initiates with this origin-specific binding disrupted, even when the disruption extends over the period of obligatory protein and ribonucleic acid synthesis that must precede initiation after release of cells from amino acid starvation. Thus the origin-associated membrane-DNA interaction is not necessary either for the initiation event itself or for the maturation of a putative initiation apparatus in E. coli.

Amino Acids↗
PubMed1978

Identification of a biochemically unique DNA-membrane interaction involving the Escherichia coli origin of replication.

DNA-membrane complexes have been obtained from Escherichia coli by using a freeze-thaw lysis procedure that avoids lysozyme and detergents. Complexes made in this manner and containing DNA near the origin of replication are uniquely sensitive to ionic strength, Pronase, and trypsin. There is approximately one such complex per chromosomal origin. The sensitivities suggest that origin-specific binding is mediated by a protein. By using these unique characteristics to distinguish origin-specific complexes from the majority of DNA-membrane binding sites, it was found that the origin-specific binding persists after termination of chromosomal replication.

Cell Membrane↗