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D Corwin

Publications and source records attributed to D Corwin.

14 recordsLinked to original sources
PubMed1997

Application of photoshop-based image analysis to quantification of hormone receptor expression in breast cancer.

The benefit of quantifying estrogen receptor (ER) and progesterone receptor (PR) expression in breast cancer is well established. However, in routine breast cancer diagnosis, receptor expression is often quantified in arbitrary scores with high inter- and intraobserver variability. In this study we tested the validity of an image analysis system employing inexpensive, commercially available computer software on a personal computer. In a series of 28 invasive ductal breast cancers, immunohistochemical determinations of ER and PR were performed, along with biochemical analyses on fresh tumor homogenates, by the dextran-coated charcoal technique (DCC) and by enzyme immunoassay (EIA). From each immunohistochemical slide, three representative tumor fields (x20 objective) were captured and digitized with a Macintosh personal computer. Using the tools of Photoshop software, optical density plots of tumor cell nuclei were generated and, after background subtraction, were used as an index of immunostaining intensity. This immunostaining index showed a strong semilogarithmic correlation with biochemical receptor assessments of ER (DCC, r = 0.70, p < 0.001; EIA, r = 0.76, p < 0.001) and even better of PR (DCC, r = 0.86; p < 0.01; EIA, r = 0.80, p < 0.001). A strong linear correlation of ER and PR quantification was also seen between DCC and EIA techniques (ER, r = 0.62, p < 0.001; PR, r = 0.92, p < 0.001). This study demonstrates that a simple, inexpensive, commercially available software program can be accurately applied to the quantification of immunohistochemical hormone receptor studies.

Breast Neoplasms↗
PubMed1987

Gonococcal pilin variants in experimental gonorrhea.

When pilus+ Gc were introduced into a male subject's urethra, they gave rise to pilus+ variants whose pilin mRNAs differed from that of input Gc. The differences stemmed from the Gc genome's single complete pilin gene having undergone gene conversion by different partial pilin genes' sequences and by different length stretches of a single partial pilin gene. In some instances, the variant's pilin mRNA appeared to reflect two independent gene-conversion events that used sequences from two different partial pilin genes. The resulting variants' pilins exhibited antigenic differences compared with the pilin polypeptide of input Gc; these differences were discernible by immunoblotting with mAbs. Amino acid and antigenic changes occurred in a segment of the variants' pilin polypeptides that previously was thought to be conserved or constant in sequence.

Amino Acid Sequence↗
PubMed1986

Gene conversion involving the pilin structural gene correlates with pilus+ in equilibrium with pilus- changes in Neisseria gonorrhoeae.

Gonococci (Gc) exhibit pilus+----pilus- "phase transitions" at high frequency, but only some of the pilus- Gc can revert to pilus+ phenotype. We examined reversible phase transitions between pilus+ Gc and a particular pilus- variant (P-rp+ phenotype) whose pilin mRNA carries a unique block of nucleotides encoding an "assembly missense" pilin polypeptide. The results show that Gc pilus+ in equilibrium with P-rp+ transitions can result from intragenic recombination in which there is nonreciprocal exchange of partially homologous DNA sequences from a partial pilin gene (in silent, storage form) into the expression locus' complete pilin gene. Hence Gc pilus phase variation, like pilus antigenic variation, can occur by gene conversion of the pilin structural gene expression locus.

Bacterial Adhesion↗
PubMed1985

Pilus- gonococcal variants. Evidence for multiple forms of piliation control.

Pilus+ to pilus- transitions of gonococci (Gc) that involve rearrangement of pilin gene DNA yield the P-n phenotype, which is incapable of reversion (to pilus+). Reversion to pilus+ is found for nonpiliated Gc that have undergone no apparent pilin gene rearrangement. Among the reverting, nonpiliated Gc, two distinct phenotypes (P-rp- and P-rp+) occur and are differentiated according to their synthesis (or lack) of pilin subunits; both P-rp- and P-rp+ Gc contain pilin-specific mRNA. The occurrence of these different pilus- phenotypes strongly suggests that several mechanisms can account for changes in the piliation status of Gc; one of these involves pilin gene rearrangement but the others apparently operate at posttranscriptional levels. Reverting pilus- Gc may have a pathogenic advantage in being able to reversibly alter their host cell adherence-promoting surface properties through high frequency transitions in piliation status.

Bacterial Outer Membrane Proteins↗
PubMed1985

Morphology of three strains of contagious equine metritis organism.

Examination of recently isolated cultures of three strains of Contagious Equine Metritis Organism grown on specially formulated, serum-free, clear typing medium revealed the presence of numerous colonial opacity variants. These colonies were prepared by a number of fixation and staining techniques and examined by scanning and transmission electron microscopy. Opaque and transparent phenotypes produced copious amounts of extracellular material compared with intermediate-opacity phenotypes which produced little or none. Also unique to intermediate colonies were numerous thin intercellular strands, which may represent pili or polymers of extracellular material. The presence of an unusual fibrillar layer (with similar electron density to the extracellular material) on the outer leaf of the outer membrane also was confirmed. A number of other ultrastructural features also were noted, including an epilayer, a thin nonmembranous layer which covered colonies and adjacent agar.

Animals↗
PubMed1978

Dexamethasone treatment during hemorrhagic shock: effects independent of increased blood pressure.

Effects of dexamethasone (5 mg/kg of body weight) on organ blood flow, enzyme release, and hemodynamics were studied in dogs with hemorrhagic shock to determine if the consequences observed were due to increased mean arterial blood pressure (MABP) or intrinsic effects of dexamethasone. Hemorrhage was induced in anesthetized dogs until the MABP was 50 mm of Hg and then the dogs were treated with dexamethasone or an equal volume of saline solution. Dogs remained connected to the blood reservoir during the entire experiment and MABP was maintained at 50 mm of Hg in the treated and control groups of dogs. Beneficial actions of dexamethasone treatment independent of increased MABP were observed. Increased survival rate, differential blood flow to some organs, and less tissue damage occurred as a result of dexamethasone treatment and were independent of increased MABP.

Amylases↗
PubMedDate not supplied

Computerized interviews as a method of assessing psychopathology in children.

A computerized version of the Diagnostic Interview for Children and Adolescents-Revised (DICA-R) has been developed. There are three versions of the interview, one for children aged 6 to 12, one for adolescents aged 13 to 18, and one for parents of children aged 6 to 18. Acceptability and reliability studies of the child and adolescent versions were performed on 93 subjects. The results show that children of all ages enjoyed the computer, and most were able to complete the interview with very little help. Reasonable reliability was found for both age groups despite difficulty with certain diagnostic criteria.

Adolescent↗
PubMedDate not supplied

Pathophysiology of the Lyme disease spirochete, Borrelia burgdorferi, in ixodid ticks.

The pathophysiology of Borrelia burgdorferi, the Lyme disease spirochete, is unique in tick/vector relationships, differing substantially from that of other spirochetes, e.g., Borrelia duttonii, the agent of tick-borne relapsing fever, and Borrelia recurrentis, the agent of louse-borne relapsing fever, in their respective vectors. Following ingestion by a tick, B. burgdorferi lodges in the midgut diverticula, in some instances penetrating the gut wall and invading various tissues. Certain investigators suggest that transmission of the spirochete occurs via infectious saliva, although, in light of the fact that only 5% of adult ticks are systemically infected, this mechanism is open to question. Alternatively, transmission may occur via periodic regurgitation of gut fluids during the feeding process. While ticks of the genus Ixodes were once thought to be the only vectors, it now appears that other genera, and possibly other hematophagous arthropods, may also be involved.

Animals↗
PubMedDate not supplied

A molecular strategy for the study of bacterial invasion.

Bacterial populations are often clonal, and even within a bacterial species, the frequency of gene exchange and recombination is quite low. Consequently, mobile genetic elements--plasmids, bacteriophages, and transposons--have been the central factors in the evolution of pathogenic traits. One central feature of pathogenicity, the capacity to enter epithelial cells, is encoded by the bacterial chromosome of Yersinia pseudotuberculosis but by plasmid genes in enteroinvasive Escherichia coli. A single Yersinia gene, inv, which encodes a single 107,000-dalton protein, can be cloned in E. coli K12, and its presence is sufficient to permit the bacteria to enter cultured human cells. In contrast, fully 70 kilobases of a virulence plasmid from enteroinvasive E. coli must be transferred to E. coli K12 to achieve the same result. While researchers are at the early stages of understanding microbial entry into host cells, they can now investigate the molecular basis of this event in greater detail than has previously been possible.

Animals↗