Biomedical subjects

C Dibble

Publications and source records attributed to C Dibble.

6 recordsLinked to original sources

PubMed2004

Detection of reflux esophagitis on double-contrast esophagrams and endoscopy using the histologic findings as the gold standard.

The purpose of our study was to determine the accuracy of double-contrast barium studies and endoscopy for detecting reflux esophagitis, using the endoscopic biopsy findings as the gold standard. A review of radiology, endoscopy, and pathology files showed 37 patients with reflux symptoms who underwent double-contrast barium studies and endoscopy with biopsy specimens from the esophagus. The radiographic images were reviewed in a blinded fashion and correlated with the endoscopic and histologic findings to determine the radiographic and endoscopic accuracies for detecting reflux esophagitis, using the endoscopic biopsy specimens as the gold standard. Double-contrast barium studies and endoscopy had low but comparable accuracies for detecting reflux esophagitis, with sensitivities of 35% and 39%, specificities of 79% and 71%, positive predictive values of 73% and 69%, and negative predictive values of 42% and 41%, respectively. When mucosa granularity was evaluated as an individual sign of esophagitis on double-contrast studies, this finding had a sensitivity of 35%, a specificity of 93%, a positive predictive value of 89%, and a negative predictive value of 46% for detecting reflux esophagitis. Our experience suggests that double-contrast barium studies and endoscopy have limited ability to detect reflux esophagitis, in particular mild esophagitis, when using the histologic findings as the gold standard. When radiographic abnormalities are detected, however, mucosal granularity is the single best sign of reflux esophagitis on double-contrast studies.

Adult↗

PubMed2000

Semaphorin 3A is required for guidance of olfactory axons in mice.

Semaphorin 3A (Sema3A) is a membrane-associated secreted protein that has chemorepulsive properties for neuropilin-1 (npn-1)- expressing axons. Although mice lacking the Sema3A protein display skeletal abnormalities and heart defects, most axonal projections in the CNS develop normally. We show here that Sema3A is expressed in the lamina propria surrounding the olfactory epithelium (OE) and by ensheathing cells in the nerve layer of the ventral olfactory bulb (OB) throughout development. Subsets of sensory neurons expressing npn-1 are distributed throughout the OE and extend fibers to the developing OB. In wild-type mice, npn-1-positive (npn-1(+)) axons extend to lateral targets in the rostral OB and medial targets in the caudal OB, avoiding regions expressing Sema3A. In Sema3A homozygous mutant mice, many npn-1(+) axons are misrouted into and through the ventral nerve layer, beginning as early as embryonic day 13 and continuing at least until birth. At postnatal day 0, npn-1(+) glomeruli are atypically located in the ventral OB of Sema3A(-/-) mice, indicating that aberrant axon trajectories are not corrected during development and that connections are made in inappropriate target regions. In addition, subsets of OCAM(+) axons that normally project to the ventrolateral OB and some lactosamine-containing glycan(+) axons that normally target the ventral OB are also misrouted in Sema3A mutants. These observations indicate that Sema3A expression by ensheathing cells plays an important role in guiding olfactory axons into specific compartments of the OB.

Animals↗

PubMed2000

Patterning of olfactory sensory connections is mediated by extracellular matrix proteins in the nerve layer of the olfactory bulb.

In early rat embryos when axons from sensory neurons first contact the olfactory bulb primordium, lactosamine-containing glycans (LCG) are detected on neurons that are broadly distributed within the olfactory epithelium, but that project axons to a very restricted region of the ventromedial olfactory bulb. LCG(+) axons extend through channels defined by the coexpression of galectin-1 and beta2-laminin. These two extracellular matrix molecules are differentially expressed, along with semaphorin 3A, by subsets of ensheathing cells in the ventral nerve layer of the olfactory bulb. The overlapping expression of these molecules creates an axon-sorting domain that is capable of promoting and repelling subsets of olfactory axons. Specifically, LCG(+) axons preferentially grow into the region of the nerve layer that expresses high amounts of galectin-1, beta2-laminin, and semaphorin 3A, whereas neuropilin-1(+) axons grow in a complementary pattern, avoiding the ventral nerve layer and projecting medially and laterally. These studies suggest that initial patterning of olfactory epithelium to olfactory bulb connections is, in part, dependent on extracellular components of the embryonic nerve layer that mediate convergence and divergence of specific axon subsets.

Age Factors↗

PubMed1999

The role of international environmental agreements in metered-dose inhaler technology changes.

Introduced in the 1950s, metered dose inhalers (MDIs) became a revolutionary way to deliver medication directly to the lungs of patients with asthma and chronic obstructive pulmonary disease. Since their initial introduction, MDIs have used chlorofluorocarbons to propel the medication out of the canister into a patient's lungs. This article presents an overview of the global transition away from the use of chlorofluorocarbon propellants in MDIs to non-ozone-depleting substitutes including hydrofluoroalkane (outside of the pharmaceutical industry and in the context of Montreal Protocol and Kyoto Protocol discussions, these gases are referred to as hydrofluorocarbons; hydrofluoroalkane-134a, for example, is referred to as hydrofluorocarbon-134a) propellants, in accordance with the terms of the international environmental agreement the Montreal Protocol on substances that deplete the ozone layer (the Montreal Protocol). This article will also describe the environmental characteristics of chlorofluorocarbons and hydrofluoroalkanes when they are used as MDI propellants. Finally, the article will review key provisions of the pending Kyoto Protocol to the United Nations Framework Convention on Climate Change (the Kyoto Protocol) that may affect the future of hydrofluoroalkanes.

Administration, Inhalation↗

PubMed1982

Mortality rate in strabismus surgery.

Strabismus surgery has been viewed as being associated with a high degree of mortality. Many past studies have used small surgical samples and have stressed the various theoretical causes of the deaths rather than view the procedure from a statistical and scientific standpoint. We present here a large series of surgical cases collected nationwide showing that strabismus surgery is a relatively safe procedure associated with a mortality less than that of a tooth extraction.

Adolescent↗

PubMed1981

Reliability of fixation disparity curves.

Fixation disparity curves were recorded in three normal subjects once per week over a period of 10 weeks. Results indicate that measurements of fixation disparity are reliable within limited ranges of forced convergence and forced divergence. Increases in the demand to maintain fusion lead to increases in observed variability of fixation disparity. It is suggested that variability of fixation disparity might be related to the ease with which the two eyes are used as a team.

Adult↗