PubMed Health⌕ Search

Biomedical subjects

C J Sullivan

Publications and source records attributed to C J Sullivan.

11 recordsLinked to original sources
PubMed2006

Measuring cell surface elasticity on enteroaggregative Escherichia coli wild type and dispersin mutant by AFM.

Enteroaggregative Escherichia coli (EAEC) is pathogenic and produces severe diarrhea in humans. A mutant of EAEC that does not produce dispersin, a cell surface protein, is not pathogenic. It has been proposed that dispersin imparts a positive charge to the bacterial cell surface allowing the bacteria to colonize on the negatively charged intestinal mucosa. However, physical properties of the bacterial cell surface, such as rigidity, may be influenced by the presence of dispersin and may contribute to pathogenicity. Using the system developed in our laboratory for mounting and imaging bacterial cells by atomic force microscopy (AFM), in liquid, on gelatin coated mica surfaces, studies were initiated to measure cell surface elasticity. This was carried out in both wild type EAEC, that produces dispersin, and the mutant that does not produce dispersin. This was accomplished using AFM force-distance (FD) spectroscopy on the wild type and mutant grown in liquid or on solid medium. Images in liquid and in air of both the wild-type and mutant grown in liquid and on solid media are presented. This work represents an initial step in efforts to understand the pathogenic role of the dispersin protein in the wild-type bacteria.

Agar↗
PubMed2006

Effect of endothelial cell-based iNOS gene transfer on cavernosal eNOS expression and mouse erectile responses.

Inducible nitric oxide synthase (iNOS) gene transfer is reported to augment erectile responses in rats, although it is also shown to impair vasorelaxation in cerebral arteries. We investigated the effect of endothelial cell-based iNOS gene transfer on endothelial NOS (eNOS) expression and mouse erectile responses. Human coronary artery endothelial cells (EC) transduced with empty vector (control) or iNOS were grown in culture and transplanted into the corpus cavernosum of severe combined immunodeficient mice. Endothelial NOS expression was compared in control and iNOS-transduced cells grown in the presence or absence of a selective iNOS inhibitor, L-N6- (1-iminoethyl) lysine hydrochloride (L-NIL). At 3-5 days after cell transplantation, we recorded intracorporal pressure (ICP) responses to cavernosal nerve stimulation and measured cavernosal total NO and eNOS protein expression. In this study, EC transduced with iNOS produced significantly more NO than controls but exhibited a twofold downregulation of eNOS protein and mRNA. This effect was reversed by L-NIL. In vivo, the cell-based gene transfer of iNOS led to significantly increased ICP responses, compared to mice transplanted with control ECs. Consistent with the in vitro data, cavernosal lysates had significantly reduced eNOS expression. In conclusion, EC gene transfer of iNOS downregulates EC expression of eNOS by an NOS-dependent mechanism. In the cavernosum of mice transplanted with Inos-transduced EC, nerve-stimulated erectile responses were augmented by the short-term gene transfer. However, our findings suggest that iNOS gene transfer may have deleterious effects on endothelial function if used as a treatment for erectile dysfunction.

Animals↗
PubMed2005

Mounting of Escherichia coli spheroplasts for AFM imaging.

The cytoplasmic membrane of Escherichia coli (E. coli) is the location of numerous, chemically specific transporters and recognition elements. Investigation of this membrane in vivo by atomic force microscopy (AFM) requires removal of the cell wall and stable immobilization of the spheroplast. AFM images demonstrate that spheroplasts can be secured with warm gelatin applied to the mica substrate just before the addition of a spheroplast suspension. The resulting preparation can be repeatedly imaged by AFM over the course of several hours. Confocal fluorescence imaging confirms the association of the spheroplasts with the gelatin layer. Gelatin molecules are known to reorder into a network after heating. Entrapment within this gelatin network is believed to be responsible for the immobilization of spheroplasts on mica.

Animals↗
PubMed1997

Influence of angiotensin II on transmission in the superior cervical ganglion.

The influence of angiotensin II (ANG II) on sympathetic ganglionic transmission was examined in the in situ, normally perfused, superior cervical ganglion in pentobarbitone-anaesthetized rabbits. Compound action potentials were evoked in the external carotid nerve by repetitive electrical stimulation of the decentralized preganglionic cervical sympathetic nerve (supramaximal intensity, 1 ms, 0.5 Hz). A continuous partial nicotinic block was maintained by intravenous infusion of hexamethonium. The converting enzyme inhibitor captopril was infused to prevent the endogenous generation of ANG II. Graduated intravenous infusion of ANG II brought about graduated increases in the height of the S2 potential; the threshold rate of infusion for this effect was 40 ng min-1. At this infusion rate, the plasma concentration of ANG II was estimated to lie between 80 and 600 pg ml-1. While ANG II can modify sympathetic ganglionic transmission, it is unlikely that it has any effect at physiological plasma concentrations of circulating ANG II reported for the rabbit (2-80 pg ml-1).

Action Potentials↗
PubMed1988

Respiratory syncytial virus infection in immunocompromised adults.

Respiratory syncytial virus disease was documented in 11 immunocompromised adults, aged 21 to 50. Underlying conditions included bone marrow transplant (6 patients), renal transplant (3 patients), renal and pancreas transplants (1 patient), and T-cell lymphoma (1 patient). Diagnosis of infection was based on specimens from bronchoalveolar lavage, sputum, throat, sinus aspirate, and lung biopsy. The virus was detected simultaneously by antibody in either an immunofluorescence or enzyme-linked immunosorbent assay in 3 of 4 patients whose culture results were positive for respiratory syncytial virus. The virus was an unexpected finding, despite widespread infection in the community. Clinical symptoms included low-grade fever, nonproductive cough, rhinorrhea or nasal congestion, and radiographic evidence of interstitial infiltrates and sinusitis. Aerosolized ribavirin therapy was used in the 6 recipients of bone marrow transplants, 3 of whom required assisted ventilation but died. Death caused by virus infection was documented in 4 of 11 patients. Respiratory syncytial virus disease must be considered in the differential diagnosis of fever and pulmonary infiltrates in immunocompromised adults.

Adult↗
PubMed1988

Diagnosis of viral pneumonia.

The diagnosis of viral pneumonia has changed during the past decade from a purely clinical diagnosis to one that is both clinical and laboratory in nature. Viral pneumonias can be divided into two clinical groups: the so-called "atypical" pneumonias in otherwise normal hosts, and viral pneumonitis in the immunocompromised host. Clinical factors such as patient age, immune status, time of year, illness in other family members, community outbreaks, onset, severity, duration of symptoms, and the presence of a rash remain important aids in diagnosing viral causes of both atypical pneumonia and pneumonia in the immunocompromised patient. However, advances in virus culture methodologies and the use of monoclonal antibodies coupled with immunofluorescence and ELISA techniques have markedly enhanced both the sensitivity, specificity, and rapidity of the diagnosis of viral pneumonias. Further advances are expected in the future as nucleic acid hybridization techniques are increasingly applied to both viral cultures and direct analysis of clinical specimens.

Adenovirus Infections, Human↗
PubMed1986

Rounded atelectasis: a new criterion for benignancy.

A malignancy must be considered whenever a mass lesion is encountered on a chest roentgenogram. Unless an unequivocal diagnosis of a benign lesion is made, thoracotomy is usually indicated. Rounded atelectasis, while only having been recently described, is being encountered with increasing frequency. As illustrated by our three cases, radiologic diagnosis of this entity is a major criterion for judging the benignity of a mass and obviates the need for a thoracotomy.

Aged↗
PubMedDate not supplied

AFM imaging of bacteria in liquid media immobilized on gelatin coated mica surfaces.

Immobilization of particulates, especially biomolecules and cells, onto surfaces is critical for imaging with the atomic force microscope (AFM). In this paper, gelatin coated mica surfaces are shown to be suitable for immobilizing and imaging both gram positive, Staphylococcus aureus, and gram negative, Escherichia coli, bacteria in both air and liquid environments. Gelatin coated surfaces are shown to be superior to poly-L-lysine coated surfaces that are commonly used for the immobilization of cells. This cell immobilization technique is being developed primarily for live cell imaging of Rhodopseudomonas palustris. The genome of R. palustris has been sequenced and the organism is the target of intensive studies aimed at understanding genome function. Images of R. palustris grown both aerobically and anaerobically in liquid media are presented. Images in liquid media show the bacteria is rod shaped and smooth while images in air show marked irregularity and folding of the surface. Significant differences in the vertical dimension are also apparent with the height of the bacteria in liquid being substantially greater than images taken in air. In air immobilized bacterial flagella are clearly seen while in liquid this structure is not visible. Additionally, significant morphological differences are observed that depend on the method of bacterial growth.

Aluminum Silicates↗