Biomedical subjects

I A Fregona

Publications and source records attributed to I A Fregona.

8 recordsLinked to original sources

PubMed2006

Peripapillary fundus perimetry in eyes with glaucoma.

AIMS: To evaluate, with fundus perimetry, the peripapillary differential light threshold (DLT) in eyes with glaucoma and ocular hypertension (OHT), and compare it with peripapillary retinal nerve fibre layer (RNFL) thickness. METHODS: 35 glaucomatous, 29 OHT and 24 control eyes were included. Peripapillary DLT at 1 degrees from the optic nerve head was quantified with fundus perimetry; peripapillary RNFL thickness was measured over the same area by optical coherence tomography. RESULTS: Mean (SD) peripapillary DLT was 19.2 (1.7), 17.6 (4.2) and 10.1 (6.9) dB in control, OHT and glaucomatous eyes, respectively (p<0.001). Mean (SD) RNFL thickness was 98.4 (35.3), 83.9 (35.1) and 55.8 (28.2) microm, respectively (p<0.001). Mean peripapillary DLT showed higher sensitivity and specificity in differentiating the three groups compared with RNFL thickness. CONCLUSION: Progressive, significant reduction of peripapillary DLT was documented in OHT and glaucomatous eyes compared with controls (p<0.001). DLT reduction parallels RNFL reduction.

Aged↗

PubMed2001

Effects of cyclosporin A on human conjunctival fibroblasts.

OBJECTIVE: To evaluate the effects of cyclosporin A (CsA) on cytokine and/or collagen production, cell growth, and apoptosis in conjunctival fibroblast cultures. METHODS: Fibroblast cultures derived from normal subjects and patients with vernal keratoconjunctivitis and pemphigoid were exposed to different concentrations of CsA for either 24 hours or 30 days. The effects were evaluated by the colorimetric MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) test to assess cell proliferation, and by the measurement of procollagen I (PIP) and procollagen III (PIIIP) cytokines and total protein in culture medium. CsA-induced apoptosis was assessed by fluorescence-activated cell sorter analysis. RESULTS: After 24 hours of exposure to doses of CsA of more than 10 microg/mL, cell proliferation and migration were significantly reduced. Cyclosporin A reduced PIP and interleukin 1 (IL-1) production in a dose-dependent manner. Interleukin 6 and IL-8 were increased by 10 microg/mL of CsA, whereas transforming growth factor beta, PIIIP, and total protein were unaffected. Cyclosporin A exposure induced apoptosis in a time- and dose-dependent manner. Long-term exposure to CsA reduced IL-6 but did not modify PIIIP production. CONCLUSION: Exposure to CsA directly modified fibroblast behavior. CLINICAL RELEVANCE: Cyclosporin A ability to accelerate apoptosis in clinically fibrotic tissues may prove to be therapeutic and useful in hyperproliferative conjunctival disorders.

Apoptosis↗

PubMed1999

Histamine effects on conjunctival fibroblasts from patients with vernal conjunctivitis.

Histamine, an important mast cell mediator in allergic disorders, may affect extracellular matrix production and cell growth in vernal keratoconjunctivitis (VKC). In the present study, the histamine reactivity of conjunctival fibroblasts derived from VKC patients was investigated in vitro. Conjunctival fibroblast cultures were derived from biopses of 8 tarsal VKC patients and 5 normal subjects. These cells were maintained in vitro and stimulated with different concentrations of histamine with and without H1 (clorpheniramine) and H2 (cimetidine) receptor antagonists. Comparisons were made to fibroblasts grown in the same media without histamine and to fibroblasts stimulated with just antihistamine. The effects of histamine were evaluated by: (1) the MTT test to assess cell proliferation; (2) an in vitro wound model for cell migration and (3) the measurement of procollagen I (PIP) and procollagen III (PIIIP) in supernatants for collagen production. Results showed: (1) While VKC-derived fibroblasts proliferated at a faster rate than normal cells in unstimulated media, after histamine stimulation, VKC and normal cells grew at a similar rate. Both H1 and H2 antagonists significantly inhibited (P<0.05) histamine-induced cell proliferation. (2) Histamine enhanced cell migration after wounding; this effect was inhibited only by H2 antagonism. (3) When stimulated with histamine, VKC fibroblasts produced significantly more PIP than those in control media. Furthermore, VKC-derived fibroblasts were more sensitive to histamine challenge, producing significantly more PIP than normal fibroblasts. H1 and H2 antagonists did not modify histamine-stimulated PIP production. The enhanced proliferative and productive capacity of VKC fibroblasts may be the result of a selective overgrowth of one or more fibroblast subpopulations in a chronically inflamed tissue. Histamine increased proliferation, migration and collagen production in both normal and VKC fibroblasts. Since H2 antagonism modulated both cell growth and migration, but not histamine-induced collagen production, the latter may be mediated by a different receptor. These results showed that histamine is at least partially responsible for fibroblast stimulation.

Cell Culture Techniques↗

PubMed1995

Histaminase activity in patients with vernal keratoconjunctivitis.

PURPOSE: To investigate the activity of histamine-degradating enzymes in tears and plasma of patients with vernal keratoconjunctivitis (VKC). METHOD: Tear and plasma samples were collected from patients with VKC and from age-matched control subjects. Histamine was measured by enzyme-linked immunosorbent assay in acid samples treated with perchloric to deactivate histaminase and in untreated samples. Tear cytology, skin test reactivity to histamine, and the sum clinical score of allergic signs and symptoms in patients with VKC also were evaluated. Nineteen patients with active VKC and six age-matched control subjects participated in this study. RESULTS: In untreated samples, tear histamine (mean +/- standard error of the mean) was 11.15 +/- 2.16 ng/ml in patients with VKC and 0.855 +/- 0.225 ng/ml in control tears (P < 0.001). In treated samples, mean tear histamine was 22.25 +/- 4.17 ng/ml in patients with VKC versus 10.64 +/- 2.85 ng/ml in control subjects (not statistically different). The ratio of histamine in treated to untreated samples (indicating histaminase activity) was significantly lower in patients with VKC (2.30 +/- 0.263) than in control subjects (17.57 +/- 5.97; P = 0.0001). Plasma histamine levels in untreated and treated samples were significantly higher in patients with VKC (untreated, 2.23 +/- 0.334 ng/ml; treated, 4.37 +/- 0.357 ng/ml) than in control subjects (untreated, 0.254 +/- 0.068, P = 0.0002; treated, 2.96 +/- 0.171 ng/ml, P = 0.0082). The enzymatic breakdown of histamine (treated/ untreated) in plasma was significantly decreased in patients with VKC (2.54 +/- 0.447) compared with control subjects (14.78 +/- 4.86; P = 0.0012). Skin reactivity to histamine was not increased in VKC. Tear histamine levels were significantly correlated to tear lymphocyte content in the general population and to tear basophils in the patients with tarsal-vernal VKC only. An increased number of tear eosinophils were correlated with elevated enzyme activity only in patients with tarsal-vernal VKC and to the clinical score only in limbal-vernal patients. CONCLUSION: The enzymatic degradation of histamine was significantly decreased in patients with VKC compared with control subjects in both tears and plasma, suggesting that this dysfunction may be a primary factor in the pathophysiology of VKC.

Adolescent↗

PubMed1993

Antigen sensitivity evaluated by tear-specific and serum-specific IgE, skin tests, and conjunctival and nasal provocation tests in patients with ocular allergic disease.

The potential for ocular allergic patients to have a site-specific antigen sensitisation was investigated using various diagnostic tests of allergen sensitivity in subjects with allergic conjunctivitis (AC: n = 135), vernal keratoconjunctivitis (VK: n = 20), rhinoconjunctivitis (n = 20) or rhinitis (N = 10). In the AC and VK patients, skin tests and conjunctival provocation tests (CPT) were performed, and the levels of specific IgE in serum and in tears were identified. A subgroup of 36 patients was also challenged with a nasal-specific provocation test (NPT). Results showed a poor correlation between skin test results and tear-specific IgE, and also between serum-specific IgE and tear-specific IgE in both AC and VK patients (K < 0.3). CPT and tear IgE were significantly correlated (K = 0.5) in the ocular allergic population. In patients with rhinoconjunctivitis or rhinitis, and in 10 normal subjects, results of CPT and NPT were in 100% agreement. Conversely, in patients with only conjunctivitis, little correlation was found between the results of CPT and NPT (K = 0.3). Tear-specific IgE was the only positive diagnostic sign of antigen sensitivity in 35% of VK patients and 30% of AC patients. These results suggest that the conjunctiva can be a uniquely sensitised target organ in allergic patients.

Conjunctiva↗

PubMed1991

Heterogeneity of lymphocytes from aqueous humor of patients with uveitis.

T lymphocyte subsets from inflammatory aqueous humor (n = 34) have shown one of three different patterns: group 1 = lower CD4+/CD8+ ratio in aqueous as compared to peripheral blood (0.43 +/- 0.25 vs. 1.96 +/- 0.82; n = 9); group 2 = similar CD4+/CD8+ ratio in aqueous and peripheral blood (1.76 +/- 0.60 vs. 1.60 +/- 0.62; n = 22); and group 3 = higher CD4+/CD8+ ratio in aqueous as compared to peripheral blood (7.53 +/- 0.47 vs. 2.13 +/- 0.55; n = 3). DR+ T lymphocytes were significantly higher, and natural killer cells significantly lower, in inflammatory aqueous as compared to peripheral blood.

Aqueous Humor↗

PubMed1990

Correlation between conjunctival provocation test (CPT) and systemic allergometric tests in allergic conjunctivitis.

In order to assess the potential usefulness of CPT as a diagnostic tool for ocular allergy, the correlation between skin/RAST tests and CPT was determined in 144 patients affected by allergic 'hay fever' type conjunctivitis. The results showed that an agreement between skin/RAST tests and CPT occurred in 71% of the cases (130/183). Of the 29% uncorrelated cases, 23% (43/183) were positive for at least one specific antigen by skin/RAST tests but not by CPT, while 6% (10/183) were positive for at least one specific antigen by CPT, but not by skin/RAST tests. CPT dramatically increased the histamine levels in tears (p less than 0.001). These findings show that (1) systemic tests can be misleading in that they may suggest a specific sensitisation which, in fact, does not involve the conjunctiva (systemic test positive/CPT negative); (2) CPT can identify local conjunctival sensitisation in the absence of a systemic sensitisation (systemic test negative/CPT positive); (3) CPT can demonstrate that allergic 'hay fever' type conjunctivitis may be related to allergens different from those responsible for a systemic sensitisation.

Adolescent↗

PubMedDate not supplied

Tear histamine and histaminase during the early (EPR) and late (LPR) phases of the allergic reaction and the effects of lodoxamide.

The objectives of this study were two-fold: to identify tear histamine content and its relationship to changes in tear histaminase activity during the early (EPR) and late phases (LPR) of the allergic reaction induced by a conjunctival provocation test (CPT) and to evaluate the effects of lodoxamide on histamine release and allergic signs and symptoms during EPR and LPR. A baseline CPT was administered to 20 allergic patients with no baseline signs or symptoms of allergy. Clinical signs and symptoms were evaluated after 20 minutes and 6 hours. Tear samples were taken after 5-10 minutes and after 6 hours for subsequent analyses of cytology and histamine content (ELISA). Patients were then randomly assigned to receive lodoxamide or placebo four times daily for one week in a double-masked fashion. A second CPT was done after this therapy and the same parameters were re-evaluated. During EPR, tear histamine increased significantly with respect to baseline values (p < 0.05). During LPR, tear histamine increased significantly (p < 0.05) only in histamine inactivated samples. Histaminase enzymes were also significantly less active during the EPR (5.5 +/- 0.7) than the LPR (9.9 +/- 2.3) and at baseline. Histamine levels significantly correlated with allergic signs and symptoms (p < 0.05) only during the EPR. Lodoxamide significantly reduced histamine release during EPR (p < 0.05), allergic signs and symptoms during both EPR (p < 0.001) and LPR (p < 0.005), and tear cytology counts during LPR. In conclusion, greater histaminase activity may account for the smaller amount of tear histamine generally found during LPR, while these enzymes seem to play less of a role during the surge of histamine release and activity in the EPR. Lodoxamide was shown to ideally inhibit various aspects of the allergic reaction: clinical signs and symptoms in both the early and late phases, the primarily EPR-related peak of histamine release, and the primarily LPR-related changes in tear cytology.

Administration, Topical↗