Decrease in vitamin C concentration in human lenses during cataract progression.

Cataract formation is believed to result from an oxidative insult which decreases the antioxidant defense of the lens, particularly the vitamin C concentration. Upon oxidation, vitamin C contributes with glucose to protein glycation. It also favours tryptophan oxidation, resulting in fluorescent peptide cross-links and protein insolubilisation. The relationship between cataract and lenticular vitamin C was analysed in 48 cataractous lens nuclei classified into four severity grades, considering the sum of the colour and opacity. Ascorbic and dehydroascorbic acids were quantified by HPLC-fluorescence. The Amadori product was measured by means of furosine, advanced glycation end products by their fluorescence and tryptophan concentration by HPLC-UV. The lens vitamin C concentration significantly decreased with cataract severity, but mostly in severe brown cataracts (around 88 mumol/100 g lens in mild cataracts, and 50 mumol/100 g in dark brown lenses). The dehydroascorbic acid concentration was always low and stable (1.9 +/- 0.9 mumol/100 g), as was the furosine concentration (0.4 +/- 0.1 mumol/g). The fluorescence of insoluble advanced glycated end products was significantly higher in severe cataracts than in milder ones. The peptide tryptophan content was stable but the tryptophan to tyrosine ratio decreased and was highly correlated to the ascorbic acid concentration. Vitamin C content appears to be a good indicator of cataract severity, suggesting that oxidation could take part in cataract progression.

[Positive diagnosis of Leber's hereditary optic neuropathy using molecular genetics]. / Diagnostic positif de neuropathie optique héréditaire de Leber par génétique moléculaire.

INTRODUCTION: Leber's hereditary optic neuropathy (LHON) is a bilateral optic atrophy, more common in males than in females. No specific clinical feature or biologic test exists to evidence LHON. We report here the case of a man affected with a nonfamilial bilateral optic atrophy, whose diagnostic remained uncertain for 17 years. PATIENT AND METHODS: This patient was hospitalized at the age of 27 in order to establish diagnosis. He had an ophthalmologic examination once a year. He was also affected with chronic renal failure. Detection of the G to A mutation at position 11778 of the DNA was assessed by restriction enzyme digestion of amplified genomic DNA. RESULTS: The 11778 mitochondrial DNA mutation was evidenced, in homoplasmic condition in white blood cells. DISCUSSION: Molecular biology allows to substantiate the diagnosis of LHON and is relatively easy and cheap. Assessment of mitochondrial DNA provides a useful diagnostic tool for nonfamilial or atypical cases of LHON.

Ocular penetration kinetics of fosfomycin administered as a one-hour infusion.

The penetration of fosfomycin in aqueous humour was studied in 21 patients who were to undergo cataract surgery. All patients received 4 grams of fosfomycin as an infusion lasting one hour. Concentrations of the drug in aqueous humour were measured 1, 2, 4, 6 and 12 hours after the start of infusion. Drug concentrations in aqueous humour and serum were measured by HPCE (High Performance Capillary Electrophoresis). The aqueous humour concentration at one hour was 11.46 mg/l +/- 2.12. Peak concentration was 14.63 mg/l +/- 5.54, reached two hours after the infusion. Concentrations were high until 6 hours and remained significant at 12 hours. These results confirm the excellent diffusion of fosfomycin in aqueous humour, with high levels at 12 hours. They justify its use in intraocular infections, by infusions repeated every eight hours, to maintain concentrations above the MIC 90 for organisms usually susceptible to the drug.

Comparative studies in hypertension under different continental conditions.

Preventive studies were undertaken according to the same protocol (questionnaire, blood pressure and cholesterol assay standardized) integrated in the Public Health Services of the GDR and Cuba. In a German community (Cottbus-Land) 5,377 people (2,340 males/3,037 females) and in the Havana region 1,179 people (437 males/742 females), all aged 30-50 years, were followed up. The Germans revealed higher proportions of hypertension and hypercholesterolemia, the Cubans those of (heavy) smoking. Conditioning factors, such as overweight, physical inactivity and psychic stress, were found to be quite differently distributed, explaining however only in part prevalence differences between the continental regions even when both sex and localization of living were considered separately.