Massimo Menzione

Effect of vitamin E on glutathione content in red blood cells, aqueous humor and lens of humans and other species

High doses of orally administered vitamin E have been given to humans, rabbits and rats. Placebo has been given to control groups. At the end of the treatment period, enhanced levels of reduced glutathione (GSH) were found in the red blood cells (humans and rabbits), aqueous humor (humans and rabbits) and lens (rabbits and rats) of treated subjects and animals. The percentage of GSH converted to oxidized glutathione (GSSG) was the same in both vitamin E-supplied and control groups. The GSSG--GSH ratio remained unchanged. The plasma levels of vitamin E were significantly higher in treated than in control subjects and animals. At the end of the study, the levels of vitamin E in aqueous humor and lens of rabbit were the same in animals which received vitamin E and in animals which received placebo. Lastly, vitamin E administration did not influence ascorbic-acid levels in plasma (humans and rabbits), aqueous humor, lens and vitreous body (rabbits).

Systemic human diseases as oxidative risk factors in cataractogenesis. I. Diabetes.

In this study we have investigated the oxidative metabolism of red blood cells (RBC), plasma, serum, aqueous humor, and lens of healthy subjects and of age-matched cataractous patients with and without diabetes. Reduced and oxidized glutathione (GSH GSSG) levels in RBC were similar among the three groups. Plasma levels of GSSG were higher in diabetics than in cataractous and control subjects. No differences in plasma content of GSH were noted among the three groups. The activity of the enzyme glucose-6-phosphate dehydrogenase was significantly diminished in diabetic patients. Controls and cataractous patients showed similar levels of malondialdehyde (MDA). Although not significant the MDA content in RBC from diabetics was elevated. No differences in plasma levels of vitamin E were noted among the three groups. The biological liquid oxidant activity of serum in diabetic patients was significantly higher than in controls and cataractous patients. GSH levels in aqueous humor were similar in diabetic and nondiabetic cataractous patients. The content of GSSG in aqueous humor was highest in diabetic patients. Control clear lenses showed low levels of MDA. The MDA levels in cataractous lenses from nondiabetic patients were significantly higher than those of controls. In diabetic patients the content of MDA in the lens was approximately twice as high as the cataractous values. Our results seem to demonstrate that oxidative damage could play a role in the pathogenesis of cataract in diabetes.

Low fluence rate photodynamic therapy combined with intravitreal bevacizumab for neovascular age related macular degeneration.

Aims To report the efficacy and safety of intravitreal bevacizumab (IVB) alone versus IVB plus low-fluence photodynamic therapy (PDT) in age-related macular degeneration (AMD) patients and to verify the occurrence of a synergistic effect of the combined approach on visual acuity, size and morphology of lesion, as well as on the treatment rate. Method Prospective comparative interventional study on 85 patients with treatment-naive classic, or predominantly classic, subfoveal choroidal neovascularisation secondary to AMD. Patients were randomly assigned to group 1 (IVB injections) and group 2 (IVB plus low fluence PDT). In group 2, the PDT with verteporfin was delivered with a low fluence rate (300 mW/cm2 for 83 s, 25 J/cm2). The follow-up was scheduled at 1, 3, 6, 9 and 12 months. Results The eye without recurrence received a mean of 2.8 (group 1) versus 1.4 (group 2) IVB injections, whereas the eyes with recurrence received a mean of 3.2 (group 1) versus 2.2 (group 2) IVB injections. The difference in reinjection rate between the two groups was statistically significant (p=0.03, ANOVA test). Visual acuity improvement was not statistically significant between the two groups (p=0.31). Conclusion The combination of IVB with low fluence PDT for the treatment of classic or predominantly classic neovascular AMD works in a synergistic fashion with a significant reduction in IVB reinjections rate.

In vitro effect of alpha-tocopherol on lysophosphatidylcholine-induced lens damage

Lysophosphatidylcholine (LPC) has been shown to be toxic to the lens in organ culture. An investigation into whether vitamin E counteracts the in vitro damaging effect of LPC on rat lenses was undertaken. A concentration higher than 10 micrograms ml-1 LPC in the culture medium is necessary to damage rat lenses, as assessed by protein content of the medium and Na+ and K+ content of the lens. Vitamin E affords its protection when present at a concentration of 10(-3) M: both the protein efflux from the lens and the lenticular cation imbalance are prevented, also if LPC concentration is 100 micrograms ml-1. This effect may be due more to the physicochemical properties of vitamin E in the stabilization of biological membranes, than to its chemical behaviour as an antioxidant.

Systemic human diseases as oxidative risk factors in cataractogenesis. II.Chronic renal failure

In this study we have investigated the oxidative metabolism of red cells (RBC), plasma, serum and aqueous humour of healthy subjects and of age-matched cataractous patients with and without chronic renal failure (CRF). Reduced glutathione (GSH) levels in RBC were lower in CRF patients than in the other groups. Oxidized glutathione (GSSG) plasma levels in CRF patients were higher than those of controls and cataractous subjects. The activity of the enzyme glucose-6-phosphate dehydrogenase in RBC was significantly reduced in CRF patients with respect to the other two groups. The levels of malondialdehyde (MDA) in RBC and in lens were about twice in CRF patients compared with the other two groups. The plasma levels of vitamin E were diminished in CRF patients; on the contrary, the biological liquid oxidant activity (BLOA) of serum in CRF patients was significantly higher than in controls and in cataractous patients without CRF. Cataractous patients with and without CRF showed similar levels of GSH in aqueous humour; on the contrary, the content of GSSG was significantly higher in CRF patients. Our findings seem to demonstrate that CRF patients are exposed to oxidative stresses that could probably act synergistically with uraemia and carbamylation of lens proteins. This synergism could explain why CRF represents a relatively high risk factor for cataract.

Effect of Topical Glucocorticoid Administration on the Protein and Nonprotein Sulfhydryl Groups of the Rabbit Lens

The effects of topical administration of glucocorticoids on rabbit lenses are described. Animals were divided into three groups. The first group (A) served as control, the second (B) and the third (C) group were treated with betamethasone and fluorometholone, respectively. After 40 days of treatment there was a significant fall in the levels of nonprotein sulfhydryl (-SH) groups (group A: 3.82 +/- 0.21; group B: 2.61 +/- 0.11; group C: 1.93 +/- 0.13 mumol/lens) and of protein -SH groups (group A: 8.215 +/- 1.023; group B: 4.120 +/- 0.631; group C: 4.068 +/- 0.538 mumol/lens). Also ascorbic acid levels showed a significant decrease both in lens and in aqueous humor. No differences were noted in the reduced glutathione content in aqueous humor. The fall in nonprotein and protein -SH could be the first event in the well-known biochemical changes that occur in steroid-induced cataract. The mechanism underlying steroid-induced damage could be due to a conformational change of lens crystallins which results in an unmasking of -SH groups with a consequent increased susceptibility to oxidation. The decrease of ascorbic acid should represent an effect of the fall in the glutathione system. Lastly, it is hypothesized that the protective effect exerted by some substances, such as vitamin E and ascorbic acid, occurs by counteracting this oxidation.

Intravitreal pegaptanib sodium (Macugen) for treatment of myopic choroidal neovascularization: a morphologic and functional study.

Background: To report the morphologic and functional outcomes resulting from the use of intravitreal pegaptanib (IVP) sodium (Macugen) in patients with myopic choroidal neovascularization. Methods: An open-label, nonrandomized, prospective clinical trial was performed. Morphologic outcome, such as foveal thickness, was assessed by optical coherence tomography, whereas functional outcomes were assessed by best-corrected visual acuity and microperimetry. Treatment protocol consisted of 3 consecutive IVP (0.3 mg/0.05 mL; baseline, 6th week, and 12th week). Follow-up checks were scheduled at the following intervals: baseline, 18, 24, 36, and 48 weeks. Results: Twenty eyes from 20 patients were studied. All patients completed follow-up at 48 weeks. After IVP, a significant decrease in foveal thickness occurred (−20%), and at the end of follow-up, choroidal neovascularization closure was obtained in all eyes. An improvement of functional parameters was recorded in all patients (best-corrected visual acuity from 25.5 ± 8.09 letters to 45.5 ± 8.16 letters, P < 0.0001; microperimetry from 8.40 ± 2.14 dB to 10.8 ± 2.05 dB, P < 0.01). The mean number of IVP was 3, and none of patients met the re-treatment criterion during the entire follow-up period. Neither ocular nor systemic side effects were observed. Conclusion: The findings demonstrate that the selective inhibition of VEGF-165 isoform by IVP is an effective treatment for myopic choroidal neovascularization.

Intravitreal bevacizumab for treatment-naive patients with subfoveal occult choroidal neovascularization secondary to age-related macular degeneration: a 12-month follow-up study.

Purpose: The aim of this study was to assess the 12-month efficacy of intravitreal bevacizumab (IVB) injection for occult choroidal neovascularization secondary to age-related macular degeneration. Methods: In this retrospective, interventional case series, 68 treatment-naïve patients with age-related macular degeneration, affected by subfoveal occult choroidal neovascularization showing recent disease progression, were monitored during the IVB protocol. The patients received 1 initial IVB injection (1.25 mg/0.05 mL), and they underwent further retreatment on a monthly basis only when necessary, according to a standardized as-required regimen, until no significant signs of choroidal neovascularization activity were present. Main outcome measures were the modifications in best-corrected visual acuity and in central retinal thickness measured by optical coherence tomography. Results: With respect to baseline, at the 12-month check, mean best-corrected visual acuity increased from 0.82 to 0.45 logMAR (P < 0.01) and mean central retinal thickness decreased from 517.0 &mgr;m to 306.5 &mgr;m (P < 0.01). To achieve these benefits, the required mean IVB number was lowered from 3.87 in the first 6 months to 1.085 in the second 6 months. A better final best-corrected visual acuity was correlated with greater best-corrected visual acuity (P < 0.005) and lesser central retinal thickness (P < 0.05) at baseline. Conclusion: In patients with age-related macular degeneration complicated by progressive occult choroidal neovascularization, first-line IVB administration represents a useful therapeutic option, especially considering its lower cost in comparison with other antiangiogenic drugs.

12-month retrospective study and review of photodynamic therapy with verteporfin for subfoveal choroidal neovascularization in age-related macular degeneration.

Purpose: To evaluate the 12-month visual outcome of photodynamic therapy with verteporfin (PDT-V) for patients with subfoveal choroidal neovascularization (CNV) secondary to age-related macular degeneration and to verify the predictive role of visual and angiographic factors. Methods: This retrospective, interventional, consecutive case series study included subjects with different forms of subfoveal CNV. All patients received PDT-V according to Treatment of Age-Related Macular Degeneration With Photodynamic Therapy/Visudyne in Photodynamic Therapy guidelines. A review of medical and angiographic records was performed. Results: Two hundred sixteen patients were divided into 4 study groups: group I, 60 eyes with classic CNV; group II, 56 eyes with predominantly classic CNV; group III, 42 eyes with minimally classic CNV; and group IV, 58 eyes with occult CNV. In groups I and II, best-corrected visual acuity (BCVA) was moderately decreased, without reaching a statistically noticeable level during the entire follow-up; lesion size reduction only reached significance in group I. Groups III and IV showed evident worsening of BCVA (P < 0.05), despite concomitant reduction in CNV size (statistically remarkable only for occult CNV). All study groups exhibited a significant correlation between higher baseline BCVA and better final visual outcome. In groups II and IV, smaller baseline CNV sizes also favorably influenced final BCVA. Conclusions: Standardized PDT-V minimizes deterioration of central vision only in patients with classic and predominantly classic CNV. Irrespective of the CNV type, better BCVA at presentation represents a good predictive sign. In predominantly classic and occult lesions, minor initial CNV dimension is also a positive prognostic element.

Changes of Some Biochemical Parameters of the Lens in Galactose-Treated Weaned Rats with and without Vitamin E Therapy

We tried to counteract the appearance of galactosemic cataracts in weaned rats by high doses of vitamin E. Rats were fed a diet containing 33% galactose. Cataract development was monitored by biomicroscopy and by several biochemical parameters: K+/Na+ ratio, aldose reductase activity, level of protein and non-protein sulfhydryl (SH) groups. Vitamin E was given parenterally at a dose of 100 mg/kg/day. The K+/Na+ ratio drops after 15 days of galactosemia, while the level of the aldose reductase rises after only 5 days of treatment. The non-protein SH groups lens contents fall from the 5th day of treatment onwards, while protein SH groups are not affected. In short-term experiments vitamin E does not prevent biochemical changes caused by galactosemia. The oxidative insult does not seem to be primarily involved in galactose cataract.