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Biomedical subjects

T Fitzgerald

Publications and source records attributed to T Fitzgerald.

At least 19 recordsLinked to original sources
PubMed2000

Inhibition of AT1 receptor internalization by concanavalin A blocks angiotensin II-induced ERK activation in vascular smooth muscle cells. Involvement of epidermal growth factor receptor proteolysis but not AT1 receptor internalization.

Recent studies of beta(2)-adrenergic receptor suggest that agonist-promoted receptor internalization may play an important role in extracellular signal-regulated kinase (ERK) activation by G protein-coupled receptors. In the present study, we explored the effects of angiotensin II (Ang II) type-1 receptor (AT(1)) internalization on Ang II-induced activation of ERK using the receptor internalization blocker concanavalin A (ConA) and the carboxyl terminus-truncated receptor mutants with impaired internalization. ConA inhibited AT(1) receptor internalization without affecting ligand binding to the receptor, Ang II-induced generation of second messengers, and activation of tyrosine kinases Src and Pyk2 in vascular smooth muscle cells (VSMC). ConA blocked ERK activation evoked by Ang II and the calcium ionophore A23187. Impairment of AT(1) receptor internalization by truncating the receptor carboxyl terminus did not affect Ang II-induced ERK activation. ConA induced proteolytic cleavage of the epidermal growth factor (EGF) receptor at carboxyl terminus and abolished Ang II-induced transactivation of the EGF receptor, which is critical for ERK activation by Ang II in VSMC. ConA also induced proteolysis of erbB-2 but not platelet-derived growth factor receptor. Thus, ConA blocks Ang II-induced ERK activation in VSMC through a distinct mechanism, the ConA-mediated proteolysis of the EGF receptor.

Angiotensin II↗
PubMed2000

Autonomic performance and dehydroepiandrosterone sulfate levels in HIV-1-infected individuals: relationship to TH1 and TH2 cytokine profile.

BACKGROUND: Products of immune activation, including cytokines and lipid membrane derivatives, have been implicated in the pathogenesis of the neurologic sequelae, including autonomic dysfunction, associated with human immunodeficiency virus 1 (HIV-1) infection. In animal models, autonomic and endocrine dysfunction are associated with an altered cytokine profile. OBJECTIVES: To investigate the relationship between markers of immune activation (beta(2)-microglobulin), HIV-1 disease progression (CD4(+) cell count and viral load), and autonomic nervous system performance and to assess the relationship between autonomic performance, plasma levels of dehydroepiandrosterone sulfate (DHEAS), and T(H)1 and T(H)2 cytokine profile. METHODS: Thirty-one HIV-1-infected individuals and 22 HIV-1-negative controls were evaluated with a comprehensive neurologic, neuropsychological, and autonomic examination. Interleukin 4 and interferon gamma were measured by enzyme-linked immunosorbent assay in the supernatant of stimulated peripheral blood mononuclear cells. RESULTS: A composite measure of autonomic performance (AZ score) was significantly lower (worse autonomic function) in patients compared with controls (P=.04). A lower AZ score was associated with higher beta(2)-microglobulin serum levels and a lower CD4(+) cell count. Interleukin 4 levels were significantly inversely associated with AZ score (P=.01), whereas interferon gamma levels were significantly positively associated with DHEAS levels (P=.04). CONCLUSIONS: Our data show significant associations between markers of immune activation and disease progression and a composite measure of autonomic function in HIV-1-infected individuals. In addition, they suggest that poor autonomic function and low DHEAS plasma levels tend to be associated with an unbalanced cytokine profile.

Adult↗
PubMed2000

The influence of long-term supplementation with biotin on the prevention of lameness in pasture fed dairy cows.

In a double-blind study, the influence of biotin supplementation on lameness in dairy cows was investigated over a 13-mo period. The experimental site was a tropical upland environment and involved over 2705 Holstein and Friesian cows on 20 participating farms. Cows on 10 farms received biotin at a rate of 20 mg/head per day in the concentrate, and cows on 10 other farms received feed without the biotin supplement. Premixes with or without biotin were incorporated into a grain concentrate that was fed at a constant rate to cows at milking. Farmers maintained accurate records of the nature of hoof problems and any treatment applied. Each herd was evaluated for locomotion scores at 8-wk intervals. Locomotion scores were significantly correlated with the number of days with measurable rainfall per month (r = 0.88). The biotin-supplemented herds exhibited better locomotion scores than the unsupplemented herds. In the wet summer period the number of lame cows, as observed by the farmer, were significantly fewer during the rainy period for the biotin-supplemented herds and required fewer antibiotic treatments than unsupplemented herds. Most hoof lesions were most commonly observed in the outer claws of the hind limb. Daily milk production (17.3 vs. 18.5 L) was not affected by biotin supplementation. Reduced milk fat percentage and somatic cell counts of bulk milk were recorded in the biotin supplemented herds during the wet, summer period.

Animal Feed↗
PubMed2000

Visceral ischemia after cardiopulmonary bypass.

The diagnosis and management of gastrointestinal complications associated with cardiopulmonary bypass is often hindered by a complicated clinical picture and equivocal examination. To better define the incidence, risk factors, and mortality, we reviewed the records of all patients undergoing cardiopulmonary bypass from 1988 through 1996. The database for this study comprised 14,521 patients who underwent cardiac surgery. The patients (543) with gastrointestinal complications were identified, and those with major complications (166) were individually reviewed. Major complications included pancreatitis, gastritis, laparotomy, gastric ulcer, cholecystitis, colonic perforation, gastrointestinal bleeding, diverticulitis, bowel obstruction, perforation, and visceral ischemia. Our results were the following. 1) Gastrointestinal complications were noted in 3.7 per cent (543) of patients with major complications occurring in 1.2 per cent. In 166 patients, 187 major complications were noted. 2) Visceral ischemia, an infrequent but usually fatal (71%) complication, occurred in 24 (0.17%). 3) Of the ischemic events, 83 per cent (20 of 24) affected the bowel; with the colon involved 80 per cent of the time (16 of 20). 4) Patients with visceral ischemia were more likely to be female (relative risk 2.1), have longer pump times (92.2 versus 74.2), have cardiac procedures other than coronary artery bypass graft (relative risk 2.6), and have end-stage renal disease (relative risk 16.7). We conclude that, given the incidence and mortality related to visceral ischemia, especially to the colon, patients with risk factors (end-stage renal disease, female sex, non-coronary artery bypass graft, and longer pump times) should undergo routine endoscopic examination of the colon early after bypass and when clinically indicated thereafter.

Aged↗
PubMed1999

Molecular evaluation of biopsy and autopsy specimens from patients receiving in vivo retroviral gene therapy.

We used the polymerase chain reaction (PCR) to assay for the presence of retroviral vector and replication-competent retrovirus (RCR) in autopsy and biopsy specimens from patients who received inoculations of retroviral vector producer cells (VPCs) into brain tumors or apparently normal tissues surrounding resected tumors. The PCR assays were capable of detecting 1 or more proviral copies of vector or RCR in 500,000 cells. Of 113 patients treated in clinical trials between 1994 and 1997, autopsy specimens were available from 32 patients. Brain tumor biopsies were also available from 24 patients. A total of 346 specimens was analyzed. Vector DNA was detected in 55% of tumor samples and 22% of brain samples obtained from resection margins. In contrast, most of the nonbrain tissues were negative for vector DNA; only low levels (<0.03%) of vector sequence were detected in 6 of 240 (2.5%) nonbrain tissues. Vector DNA was not detected in gonadal tissues from 12 men and 10 women. More importantly, RCR was not detected in any of the 134 biopsy and autopsy tissues tested, including all brain tumor, brain, and gonadal specimens. These results comprise the largest data set on molecular analysis of autopsy specimens from patients receiving retroviral gene therapy and indicate that distribution of retroviral vectors following injection of high doses of VPCs is limited to the site of inoculation.

Autopsy↗
PubMed1999

Detection of intracellular antigen-specific cytokines in human T cell populations.

Determination of antigen-specific cytokine responses of T lymphocytes after vaccination is made difficult by the low frequency of responder cells. In order to detect these responses, the profile of intracellular cytokines was analyzed using flow cytometry after antigenic expansion. Peripheral blood mononuclear cells were stimulated with antigens for 5 days, further expanded with interleukin (IL)-2, and then restimulated on day 10. Cytokine production was detected by intracellular staining with monoclonal antibodies after saponin-based permeabilization. Influenza expansion resulted in specific interferon-gamma (IFN-gamma) production of 6%-20%, with less IL-4 production (0%-2%). Tetanus toxoid resulted in even greater production. IL-4 and IFN-gamma were produced mainly by memory cells of the CD45RO+ phenotype. IFN-gamma production was contributed by both CD4 and CD8 populations. These methods were then applied to a clinical trial of a candidate human immunodeficiency virus type 1 vaccine. Antigen-specific increases in IFN-gamma were measured, which corresponded to antibody production, lymphoproliferation, and skin testing.

AIDS Vaccines↗
PubMed1999

Bacterial endotoxin is an active component of cigarette smoke.

BACKGROUND: Chronic bronchitis in cigarette smokers shares many clinical and histologic features with environmental lung diseases attributed to bacterial endotoxin (lipopolysaccharide [LPS]) inhalation. Experimental LPS inhalation mimics many of the acute effects of cigarette smoke in the lower airway. Therefore, we reasoned that LPS may be a biologically active component of cigarette smoke. DESIGN: The Limulus amebocyte lysate (LAL) assay was used to measure LPS in the tobacco and filter tip components of unsmoked 1R4F experimental cigarettes and commercially available "light" cigarettes, as well as in mainstream (MS) and sidestream (SS) smoke particles generated with an automated smoking machine and collected on ventilator mainflow filters. SETTING AND PARTICIPANTS: Blood LPS activity and plasma cytokine concentrations were measured in groups of healthy smokers and nonsmokers who reported to the walk-in clinic at the Baltimore VA Medical Center for unrelated complaints. MEASUREMENTS: Blood LPS levels were measured by LAL assay and plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), soluble TNF receptors I and II (sTNFR I and sTNFR II) were measured by enzyme-linked immunosorbent assay. RESULTS: Bioactive LPS was detected in both the tobacco portion (1R4F, 17.8+/-1.0 microg/cigarette; light, 26.8+/-7.3 microg/cigarette [mean+/-SE]) and filter tips (1R4F, 0.67+/-0.55 microg/cigarette; light, 0.70+/-0.39 microg/cigarette) of cigarettes. Bioactive LPS was also detected in both MS (1R4F, 120+/-64 ng/cigarette; light: 45.3+/-16 ng/cigarette) and SS smoke (1R4F, 18+/-1.5 ng/cigarette; light: 75+/-49 ng/cigarette). Although systemic absorption of inhaled LPS may occur, we failed to detect any differences between nonsmokers and smokers in median blood LPS levels (median values, 66.75 and 72.1 pg/mL, respectively; p = 0.55) or plasma concentrations of TNF-alpha (0 vs 0 pg/mL, respectively; p = 0.71), sTNFR I(1,469 vs 1,576 pg/mL, respectively), sTNFR II (2,011 vs 3,110 pg/mL, respectively), or IL-6 (8.8 vs 0 pg/mL, respectively; p = 0.20). CONCLUSIONS: Smoking one pack of cigarettes per day delivers a dose of respirable LPS that is comparable to the levels of LPS associated with adverse health effects in cotton textile workers. Thus, we suggest that the bioactive LPS in cigarette smoke may contribute to the pathogenesis of chronic bronchitis that develops in susceptible cigarette smokers.

Bronchitis↗
PubMed1998

Cytomegalovirus-specific IFNgamma and IL-4 are produced by antigen expanded human blood lymphocytes from seropositive volunteers.

The cytokine responses to cytomegalovirus (CMV) antigen in seropositive and seronegative individuals were measured using a combination of antigenic expansion and intracellular staining. Intracellular IFNgamma and IL-4 were produced in a dose-dependent manner by T cells in response to CMV only in the seropositive population. The potential for individual cells to produce both Th1 and Th2 cytokines simultaneously was clear, as IL-4 was most often produced in those cells with the highest IFNgamma production. The cytokine-specific nature of this response was demonstrated by fluorescence microscopy, which showed granular cytoplasmic staining, and at the mRNA level by ribonuclease protection assays. These methods expand our ability to evaluate the immune response to CMV, and can now be correlated to a number of clinical conditions.

Adult↗
PubMed1998

Highly active antiretroviral therapy results in a decrease in CD8+ T cell activation and preferential reconstitution of the peripheral CD4+ T cell population with memory rather than naive cells.

OBJECTIVE: Highly active antiretroviral therapy (HAART) can produce marked increases in peripheral blood CD4+ T cells and decreases in HIV plasma RNA copy numbers. However, it is not clear whether these absolute changes will be accompanied by a recovery in the known naive CD4+ T cell depletion or a decrease in the marked CD8+ T cell activation. DESIGN: Twenty-nine patients were enrolled in studies of either nucleoside therapy alone or nucleoside therapy combined with a protease inhibitor (zidovudine + lamivudine + indinavir). One hundred and ninety-one examinations were carried out at three baseline time points and during 40 weeks of follow-up to evaluate the effect of HAART on CD4+ memory/naive phenotype and CD8+ T cell activation. METHODS: CD4+ and CD8+ T cell number, CD62L/CD45RA expression on CD4+ T cells and CD38 expression on CD8+ T cells were measured by three-color flow cytometry. RESULTS: Most protease inhibitor treated patients had a significant rise in CD4+ numbers. The marked rise in the CD4+ T cells seen in individuals in this study was not accompanied over a 40-week period by a change in the abnormally low CD4+ naive compartment, and thus was almost completely of memory phenotype. The CD38 expression on CD8+ cells fell during treatment, and decreased to a greater degree than the comparable rise in CD4+ T cell counts. This decrease continued in many patients after the CD4+ T cell rise or viral load decline had plateaued. CONCLUSION: HAART results in changes in activation to a greater extent than absolute changes in CD4+ T cell numbers, but is not accompanied by an increase in naive CD4+ T cells. Measurements of CD4+ T cell numbers alone may not allow appropriate interpretation of immune activation or immune competence in patients receiving those drugs.

Anti-HIV Agents↗
PubMed1998

Th1/Th2 cytokine responses following HIV-1 immunization in seronegative volunteers. The AIDS Vaccine Evaluation Group.

The Th1/Th2 profile that follows human vaccination may profoundly influence the subsequent course of disease after infection. However, the ability to detect IL-4 has been limited outside trials of live vaccination. By using methods in which memory effector cells are allowed to antigenically expand by short term culture, followed by low-dose mitogenic stimulation, we have been able to follow the Th1/Th2 profile in HIV-1 volunteers enrolled in two phase I studies of HIV immunogens (a recombinant gp120 and a multivalent, octomeric V3 loop peptide). Antigen-specific interferon-gamma (IFN-gamma) could be detected in primary stimulation, but IL-4 was observed only after antigenic expansion and restimulation. In both of these studies the responses after initial immunizations were dominated by IFN-gamma, with IL-4 appearing only after multiple rounds of immunization, and IL-4 was temporally related to antibody production. Concomitant with the IL-4 production, the amount of supernatant IFN-gamma declined. Antigen-specific IL-10 was not detected in either study. Such techniques, which have been shown to correlate with outcomes in immunotherapy, may prove useful as future surrogates of human vaccine response.

AIDS Vaccines↗
PubMed1997

Glucocorticoids induce beta2-adrenergic receptor function in human nasal mucosa.

Glucocorticoids are hypothesized to induce beta2-adrenergic receptors (beta2-R) and their functions. The ability of dexamethasone (DEX) in vitro and beclomethasone dipropionate (BDP) in vivo to induce beta2-R messenger RNA (mRNA) and function was investigated in human nasal mucosa. In this tissue, albuterol does not stimulate exocytosis either in vivo or in vitro (Mullol and coworkers, 1992). Therefore, induction of beta2-R-mediated glandular exocytosis by glucocorticoids was proposed as an unambiguous outcome measure. Human nasal mucosa was cultured for 3 d with and without 1 microM DEX, then challenged with media or 100 microM albuterol. Culture supernatants were collected for measurement of exocytosed glandular products. Explant mRNA was extracted for reverse transcriptase-polymerase chain reaction (RT-PCR), and in situ hybridization of beta2-R mRNA performed. In vivo, normal subjects received saline or BDP for 3 d before albuterol nasal provocation. Concentrations of exocytosed products were measured in nasal secretions. RNA was extracted from nasal epithelial scrapings for RT-PCR. In vitro, DEX treatment induced albuterol-mediated glandular exocytosis (p < 0.04), and increased the steady-state beta2-R/beta-actin mRNA ratio (p < 0.05), and expression of beta2-R mRNA in glands. In vivo, BDP increased the beta2-R/beta-actin mRNA ratio in epithelial scrapings (p < 0.04), but did not induce albuterol-mediated glandular secretion. We conclude that glucocorticoids increase steady-state beta2-R mRNA levels in vivo and in vitro, and can induce beta2-R function as assessed by submucosal gland exocytosis in vitro. While topical BDP induced epithelial beta2-R mRNA, it did not modulate exocytosis from the deeper submucosal glands.

Administration, Topical↗
PubMed1995

Reactions to impaired fertility: the vicissitudes of primary and secondary control appraisals.

Recent formulations about how perceived control influences adaptation to chronic medical conditions suggest that although a sense of personal (primary) control may decline over time, there are ample opportunities for individuals to make other adaptation-enhancing "secondary control" appraisals such as construing benefits or finding meaning in their threatening circumstance. We describe a longitudinal study of men and women with impaired fertility that evaluates a dynamic relation between primary and secondary control--one in which anticipated benefits increase over time as failed efforts to achieve a desired pregnancy lead to declines in primary control. Forty-six men and women with impaired fertility rated their sense of personal control over fertility outcomes, the extent to which they anticipated benefits in this situation and their outcome expectancy on two occasions separated by 14 months. As predicted, perceived control diminished over time. Changes in anticipated benefits were unrelated to changes in personal control. Anticipating benefits, however, was inversely related to changes in outcome expectancy, such that a more pessimistic expectancy over time was associated with an increase in anticipated benefits. This relation was independent of perceived control and was not mood dependent. We discuss these findings in terms of current theories of control, the need for further longitudinal investigations to evaluate the temporal relations between primary and secondary control appraisals, and implications for infertility research.

Adaptation, Psychological↗