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Biomedical subjects

M G Bucci

Publications and source records attributed to M G Bucci.

At least 37 records · Page 2Linked to original sources
PubMed1997

Nerve growth factor (NGF) reduces and NGF antibody exacerbates retinal damage induced in rabbit by experimental ocular hypertension.

BACKGROUND: It has been shown that intravitreal injection of NGF inhibits ganglion cell degeneration after optic nerve transection and ischemic injury. The aim of our study was to investigate the presence of NGF in aqueous humor and its involvement in retinal damage during ocular hypertension. METHODS: We used an experimental model of ocular hypertension in rabbit. Before treatment and 4, 10 and 15 days after induction of hypertension, we evaluated histological retinal damage and NGF levels in aqueous humor using an immunoenzymatic assay. Polyclonal anti-NGF antibodies were injected intravitreally into one eye of each rabbit (n = 6), and the animals were killed after 4 days of hypertension. Another group of rabbits (n = 12) was injected retro-ocularly with NGF and killed after 10 or 15 days of treatment for histologic evaluation of the retina. RESULTS: Our data show that experimental ocular hypertension in adult rabbits induces retinal damage and enhances local NGF levels. The highest NGF value was found after 4 days of intraocular hypertension: high levels persisted, though to a lesser extent, for up to 15 days. Histological examination revealed that the number of retinal ganglion cells (RGC) remained unchanged during the first 4 days but decreased at 10 days. These studies also showed that retro-ocular administration of NGF reduced RGC loss, whereas intraocular injection of NGF antibodies, which inhibited the endogenous NGF, exacerbated the retinal insult. CONCLUSION: These findings demonstrate a protective effect of NGF on RGC damaged by ocular hypertension and prompt further investigations to evaluate a possible therapeutic use of NGF to retard RGC death in humans.

Animals↗
PubMed1997

Efficacy of lodoxamide eye drops on mast cells and eosinophils after allergen challenge in allergic conjunctivitis.

PURPOSE: The purpose of the study is to evaluate in a double-blind, randomized study the efficacy of lodoxamide tromethamine 0.1% versus placebo. METHODS: Signs and symptoms, tear tryptase, and tear fluid cytology were evaluated in 20 asymptomatic subjects with allergic conjunctivitis. The study included three allergen challenges in skin test-positive patients. At the first visit, a threshold dose of allergen was established. At the second visit, a bilateral ocular challenge was performed without pretreatment. At the third visit, either lodoxamide or placebo eye drops were used for 1 week before ocular challenge. RESULTS: Lodoxamide significantly reduced tryptase levels (P < 0.01), neutrophils (P < 0.04), and eosinophils (P < 0.01) in the tear fluid and significantly inhibited ocular itching (P < 0.02) when compared with that of placebo. CONCLUSIONS: Lodoxamide is effective in reducing tryptase levels and the recruitment of inflammatory cells in the tear fluid after allergen challenge.

Administration, Topical↗
PubMed1997

Electrophysiological assessment of visual function in IDDM patients.

Various electrophysiological tests have been employed to reveal functional abnormalities at different levels of the visual system in insulin-dependent diabetic (IDDM) patients. The aim of our work was to assess, with a comprehensive neurophysiological protocol evaluating the retinal, macular and visual pathways functions, whether and when such electrophysiological abnormalities do appear in IDDM patients free of any fluorangiographic sign of retinopathy with various disease duration. Flash-electroretinogram (ERG), oscillatory potentials (OPs), pattern-electroretinogram (PERG), and visual evoked potentials (VEPs) in basal condition and after photostress were assessed in 12 control subjects (C) and 42 aged-matched IDDM patients without clinical retinopathy (DR-) divided, on the basis of the disease duration, into 4 groups (1-5, 6-10, 11-15, 16-20 years). In addition another age-matched group of IDDM patients with a background retinopathy (DR+; n = 12; duration of disease 18 +/- 49 years) was evaluated. In all IDDM DR-patients PERG and VEP were significantly impaired. In addition, groups 11-15 and 16-20 years displayed impaired OPs. All electrophysiological parameters were further impaired in DR+ patients. In conclusion, retinal, macular and visual pathways functions are differently impaired in IDDM (DR-) patients with different disease duration. Electrophysiological impairment starts in the nervous conduction of the visual pathways with an early involvement, goes on in the innermost retinal layers and in the macula and ends in the middle and outer retinal layers.

Adult↗
PubMed1995

Electrophysiological assessment of visual function in newly-diagnosed IDDM patients.

Electrophysiological tests (electroretinogram, oscillatory potentials, visual evoked potentials, in the basal condition and after photostress) reveal an abnormal function of the visual system in insulin-dependent diabetic (IDDM) patients. The aim of our work was to assess whether electrophysiological abnormalities in visual function exist in newly-diagnosed diabetic patients free of any fluorangiographic signs of retinopathy. Ten control subjects (age 28.7 +/- 2.44 years) and then IDDM patients (age 25.2 +/- 6.78 years; disease duration 5.3 +/- 3.5 months) in stable metabolic control (HbA1C 7.5 +/- 1.1%) were evaluated. Flash-electroretinograms and oscillatory potentials were similar in both groups. Visual evoked potentials (VEP) recorded under basal conditions showed that P100 latency was significantly increased in the diabetic patients compared to control subjects (p < 0.01), while N75-P100 amplitude was similar in both groups. The recovery time of VEP after photostress was equivalent in diabetic patients and control subjects. The impaired basal VEPs suggest an early involvement of the nervous conduction in the optic nerve. However, the preserved flash-electroretinogram and the normal recovery time after photostress indicate that a short disease duration does not induce physiopathological changes in the outer retinal layers or in the macular function.

Adult↗
PubMed1994

Visual evoked potentials after photostress in insulin-dependent diabetic patients with or without retinopathy.

Visual evoked potentials (VEPs) were assessed under basal conditions and after photostress in normal control subjects, in insulin-dependent diabetic patients with retinopathy (IDDPWR) and in insulin-dependent diabetic patients without retinopathy (IDDP). The VEPs recorded under basal conditions showed a P100 latency significantly higher in IDDP and IDDP-WR eyes than in control eyes and in IDDPWR than in IDDP eyes (P < 0.01). N75-P100 amplitude was significantly lower in IDDP and IDDPWR eyes than in control eyes (P < 0.01). No difference was recorded in the N75-P100 amplitudes between IDDP and IDDPWR eyes. In all eyes, the VEPs recorded after photostress showed an increase in latency and a decrease in amplitude. In both IDDPWR eyes and IDDP eyes VEPs recorded at 20, 40 and 60 s after photostress showed higher mean increments in P100 latency than in C control eyes, and IDDPWR eyes showed higher mean increments in P100 latency than IDDP eyes (IDDP vs control P < 0.01, IDDPWR vs control P < 0.01, IDDPWR vs IDDP P < 0.017). The mean reductions in amplitude observed at 20, 40 and 60 s after photostress in IDDP and IDDPWR eyes were lower than in control eyes (IDDP vs control P = 0.01, IDDPWR vs control P < 0.01, IDDPWR vs IDDP P < 0.01). VEPs were superimposable on the basal VEP (recovery time) at 73.9 s in control eyes, at 88.17 s in IDDP eyes and at 113.3 s in IDDPWR eyes. VEPs after photostress in IDDP patients with normal visual acuity and no fluorangiographic signs of retinopathy may show multiple modifications. This may indicate the presence of an early functional deficiency of the central retinal layers.

Adult↗
PubMed1994

The effect of increased intraocular pressure on pulsatile ocular blood flow in low tension glaucoma.

In the present study the relationship between intraocular pressure (IOP) and pulsatile ocular blood flow (POBF) in low tension glaucoma (LTG) has been investigated. The POBF was measured using the Ocular Blood Flow system of Langham in undisturbed eyes and repeated at IOP increments of about 5 and 10 mmHg in 20 patients affected with bilateral LTG and in 25 healthy subjects matched for age, IOP, refractive error, arterial blood pressure and heart rate. The POBFs were 740.1 (SD 58.83) and 667 (SD 108) microliters/minute (microliter/min) in the control and LTG groups, respectively and statistically significantly different. The POBFs at an IOP increased by 5 mmHg were 658.1 (SD 60.2) and 457.3 (SD 74.8) microliter/min in the control and LTG groups, respectively; in the control group the mean POBF at an IOP increment of 10 mmHg was 552.1 microliters/min (SD 66.9), and in the LTG group was 317.7 microliters/min (SD 85.2). Statistical analysis of the data showed a significant difference of POBFs in the two groups either at an IOP increment of 5 or 10 mmHg (p < 0.0001). The substantial decrease of POBF with increased IOP in LTG eyes compared with normals shows an altered response of the vascular system in LTG. These findings are probably consistent with a lack of the myogenic autoregulation in reply to IOP-induced modifications of the perfusion pressure.

Analysis of Variance↗
PubMed1994

Surgical avulsion of the iris to treat selected cases of neovascular glaucoma.

Surgical avulsion of the iris was performed in 11 eyes of 11 patients affected with diabetic retinopathy, rubeosis of the iris and neovascular glaucoma that had been unsuccessfully treated otherwise. Nine eyes had extensive iris neovascularization, complicated cataract and vitreous haemorrhage, whereas the other two eyes were aphakic and had previously undergone vitrectomy, lensectomy and extensive laser photocoagulation. Prior to surgical avulsion of the iris, all eyes received topical and entheric hypotensive therapy. The intraocular pressure (IOP) ranged from 24 to 52 mmHg. Iris avulsion lowered the IOP in 9 of the 11 eyes treated (IOP range, 6-19 mmHg).

Adult↗
PubMed1993

Color Doppler assessment of normal ocular blood flow.

The purpose of this study was to determine the role of CDI in the assessment of normal ocular vasculature. Color and pulsed Doppler examinations were performed in 20 healthy subjects. The principal orbital vessels were detected: ophthalmic, central retinal, lacrimal, and posterior ciliary arteries and, in a small percentage, superior ophthalmic, central retinal, and vortex veins; blood flow of arterial vessels was studied by measuring TAV, St, PS, MD, ED, PI, and RI; the morphology of the spectral waveform also was investigated. Our results suggest that duplex color Doppler may be of value in ocular vasculature examination.

Blood Flow Velocity↗
PubMed1992

Conjunctival hyperresponsiveness to ocular histamine challenge in patients with vernal conjunctivitis.

We compared the conjunctival responsiveness to histamine diphosphate in patients with vernal conjunctivitis and in healthy control subjects. Fourteen asymptomatic patients with vernal conjunctivitis and 10 healthy volunteers were challenged in one eye with 10 microliters of increasing doses (0.01, 0.05, 0.5, and 1 mg/ml in phosphate-buffered saline) of histamine diphosphate. The contralateral eye was challenged with the diluent only. Photographs of each eye were taken for evaluation of conjunctival redness by two masked investigators. Both patients with vernal conjunctivitis and control subjects reacted to histamine with a dose-dependent conjunctival redness 2 to 5 minutes after ocular challenge. Conjunctival redness was more intense in patients with vernal conjunctivitis than in control subjects after ocular challenge with 0.01 and 0.05 mg/ml of histamine diphosphate solution (p less than 0.05). Moreover, the threshold concentration of histamine diphosphate, extrapolated from each individual dose-response curve, was significantly (p less than 0.02) lower in patients with vernal conjunctivitis than in control subjects. Our findings suggest that patients with vernal conjunctivitis demonstrate conjunctival hyperresponsiveness to a nonspecific challenging agent. Nonspecific conjunctival hyperreactivity, a novel concept in allergic eye disease, may be relevant for a better understanding of the pathogenesis and clinical variability of vernal conjunctivitis.

Adolescent↗
PubMed1992

Visual evoked potentials after photostress in patients with primary open-angle glaucoma and ocular hypertension.

Visual evoked potentials (VEPs) were assessed in basal condition and after photostress in normal subjects, in subjects with ocular hypertension (OHT), and in subjects with primary open-angle glaucoma (POAG). The VEPs recorded in basal condition showed that in patients with OHT and POAG a latency of the P100 peak was higher than in controls. The amplitudes were reduced in POAG patients but not in OHT patients. In all eyes, the VEPs recorded 20 s after photostress showed an increase in latency and a decrease in amplitude. In the control eyes, the functional recovery was complete after 80 s. In the eyes with OHP and in the eyes with POAG, the parameters of VEP after photostress underwent greater changes than in the control eyes. VEPs were superimposable on the basal condition (recovery time) at 73.2 s in OHT patients and at 113.2 s in POAG patients. The longer VEP recovery time after photostress observed in OHT and POAG patients could be attributed to the reduced functionality of the outer layers or the inner retinal layers of the central retina, or both. This test may be useful in the clinical evaluation for early diagnosis of glaucoma.

Adult↗
PubMed1990

Allergen dose response and late symptoms in a human model of ocular allergy.

Eleven ryegrass-sensitive patients were challenged weekly for 4 weeks with incremental doses of ryegrass allergen applied topically to one eye; a buffer was applied to the other eye. A clinical examination and tear-fluid cytology were performed before challenge and at 20 minutes, 1 hour, and 6 hours after challenge. A significant clinical reaction and neutrophil accumulation in the tear film occurred at 20 minutes. At 1 hour, a clinical response and tear cytologic reaction were present only at higher antigen concentrations. Six hours after antigen challenge, only the highest allergen concentration (320,000 BU/ml) produced a clinical late-phase reaction (LPR) (p less than 0.01) and tear cytologic change (presence of eosinophils and lymphocytes). Five nonryegrass-sensitive control subjects were unresponsive to a similar challenge. These results indicate that a conjunctival response to allergen challenge is dose dependent, that is, the higher the dose, the more likely an LPR will occur and that an LPR correlates with significant numbers of inflammatory cells in the tear film.

Adolescent↗
PubMed1989

Conjunctival provocation test as a model for the study of allergy and inflammation in humans.

The clinical response after allergen challenge and immunologic mechanisms leading to tissue inflammation have been extensively studied in the skin, nose and lung of allergic subjects. The present paper reviews personal studies aimed at evaluating clinical, cellular and humoral events after administration of specific allergen to the eye. Specific conjunctival provocation tests performed in grass-sensitive patients caused persisting inflammatory changes in conjunctival scrapings and tear fluid with a significant accumulation of different inflammatory cells depending on the time of observation (neutrophils, 20 min; eosinophils, 6 h; neutrophils, eosinophils and lymphocytes, 12-24 h after provocation). Increasing the dose of allergen resulted in a dose-dependent increase in the number of inflammatory cells recruited. When high doses of allergen were used, the challenge not only induced late-phase histological changes, but also clinical symptoms 6-10 h after provocation. Several mediators of allergic inflammation, such as histamine, C3a des-Arg, leukotrienes B4 and C4, were also present and could be measured in tears after allergen challenge. Our studies represent the first evidence in humans that a late phase of allergic reaction occurs in the eye. They also suggest that the conjunctival provocation test may represent a model for the study of cells and mediators involved in the pathophysiology of allergic inflammation as well as of its pharmacologic modulation.

Allergens↗
PubMed1988

Flash and pattern electroretinograms during and after acute intraocular pressure elevation in cats.

Retinal functionality during short-term intraocular pressure (IOP) elevation and simultaneous systemic blood pressure (BP) variations was evaluated in the cat by recording the electroretinogram in response to both homogenous flickering light (FERG) and contrast reversing gratings (PERG). The mean arterial blood pressure (BPm) was pharmacologically adjusted to different levels and a large range of IOP values was tested. Results indicate that both FERG and PERG responses are impaired when the eye perfusion pressure (PP = BPm - IOP) is reduced and they disappear at a critical PP value of about 20 mm Hg, irrespective of the absolute value of the IOP. In addition, when the critical perfusion pressure is maintained for periods longer than 5 min, the recovery of the PERG response, when present, is always delayed compared to the full recovery of the FERG response. These findings support the hypothesis that vascular factors, ie, the impairment of the retinal blood supply, may be responsible for the disappearance of the retinal electrical activity during short-term IOP elevation. Furthermore, the retinal ganglion cells, presumably the main source of the PERG response, appear less likely to recover from the acute ischemic episode.

Acute Disease↗