Macular pigment and lutein supplementation in retinitis pigmentosa and Usher syndrome. (57/470)

PURPOSE: To determine macular pigment (MP) in patients with inherited retinal degeneration and the response of MP and vision to supplementation of lutein. METHODS: Patients with retinitis pigmentosa (RP) or Usher syndrome and normal subjects had MP optical density profiles measured with heterochromatic flicker photometry. Serum carotenoids, visual acuity, foveal sensitivity, and retinal thickness (by optical coherence tomography [OCT]) were quantified. The effects on MP and central vision of 6 months of lutein supplementation at 20 mg/d were determined. RESULTS: MP density in the patients as a group did not differ from normal. Among patients with lower MP, there was a higher percentage of females, smokers, and light-colored irides. Disease expression tended to be more severe in patients with lower MP. Inner retinal thickness by OCT correlated positively with MP density in the patients. After supplementation, all participants showed an increase in serum lutein. Only approximately half the patients showed a statistically significant increase in MP. Retinal nonresponders had slightly greater disease severity but were otherwise not distinguishable from responders. Central vision was unchanged after supplementation. CONCLUSIONS: Factors previously associated with lower or higher MP density in normal subjects showed similar associations in RP and Usher syndrome. In addition, MP in patients may be affected by stage of retinal disease, especially that leading to abnormal foveal architecture. MP could be augmented by supplemental lutein in many but not all patients. There was no change in central vision after 6 months of lutein supplementation, but long-term influences on the natural history of these retinal degenerations require further study.  (+info)

Inverse associations between plasma lycopene and other carotenoids and prostate cancer. (58/470)

Although dietary intake of tomatoes and tomato products containing lycopene has been reported to reduce the risk of prostate cancer, few studies have been done on the relationship between plasma lycopene and other carotenoids and prostate cancer. This case-control study was conducted to investigate the effects of plasma lycopene, other carotenoids, and retinol, as well as alpha- and gamma-tocopherols on the risk of prostate cancer. The study included 65 patients with prostate cancer and 132 cancer-free controls; all of them were interviewed using a standard epidemiological questionnaire at the Memorial Sloan-Kettering Cancer Center from 1993 to 1997. Plasma levels of carotenoids, retinol, and tocopherols were measured by high performance liquid chromatography. An unconditional logistic regression model was used in bivariate and multivariate analyses using Statistical Analysis System (SAS). After adjusting for age, race, years of education, daily caloric intake, pack-years of smoking, alcohol consumption, and family history of prostate cancer, significantly inverse associations with prostate cancer were observed with plasma concentrations of the following carotenoids: lycopene [odds ratio (OR), 0.17; 95% confidence interval (CI), 0.04-0.78; P for trend, 0.0052] and zeaxanthin (OR, 0.22; 95% CI, 0.06-0.83; P for trend, 0.0028) when comparing highest with lowest quartiles. Borderline associations were found for lutein (OR, 0.30; 95% CI, 0.09-1.03; P for trend, 0.0064) and beta-cryptoxanthin (OR, 0.31; 95% CI, 0.08-1.24; P for trend, 0.0666). No obvious associations were found for alpha- and beta-carotenes, retinol, and alpha- and gamma-tocopherols. Our study confirmed the inverse associations between lycopene, other carotenoids such as zeaxanthin, lutein, and beta-cryptoxanthin, and prostate cancer. This study provides justification for further research on the associations between lycopene and other antioxidants and the risk of prostate cancer.  (+info)

Developmental changes due to long-distance movement of a homeobox fusion transcript in tomato. (59/470)

Long-distance movement of RNA through the phloem is known to occur, but the functional importance of these transported RNAs has remained unclear. Grafting experiments with a naturally occurring dominant gain-of-function leaf mutation in tomato were used to demonstrate long-distance movement of mutant messenger RNA (mRNA) into wild-type scions. The stock-specific pattern of mRNA expression was graft transmissible, indicating that the mRNA accumulation pattern is inherent to the transcript and not attributable to the promoter. The translocated mRNA caused changes in leaf morphology of the wild-type scions, suggesting that the translocated RNA is functional.  (+info)

Serum carotenoid depletion follows first-order kinetics in healthy adult women fed naturally low carotenoid diets. (60/470)

Dietary intakes of carotenoids are highly variable in human populations as are serum carotenoid concentrations. However, there are few controlled data relating carotenoid intake to concentration. Most of the data that are available are from measurements of the absorption and decay of large pharmacologic doses of carotenoids, and are therefore of unknown physiologic relevance. Our objective was to determine the half-life (t(1/2)) of the most abundant carotenoids in blood serum from healthy adult women living under controlled conditions. As part of two carotenoid isotopic studies, we measured serum concentrations of beta-carotene, alpha-carotene, lutein, zeaxanthin, beta-cryptoxanthin and lycopene in 19 healthy young adult women that were fed controlled low carotenoid diets for approximately 10 wk. All other nutrients (vitamins A, E and C) were provided at 100-150% of the 1989 U.S. recommended dietary allowance levels. Exercise and activities were controlled throughout the studies to simulate usual activity patterns. Carotenoid concentrations were measured by reversed-phase HPLC. Serum carotenoid concentration decreases during depletion followed first-order kinetics. The half-lives determined in decreasing order were as follows: lutein (76 d) > alpha-carotene (45 d) = beta-cryptoxanthin (39 d) = zeaxanthin (38 d) = beta-carotene (37 d) > lycopene (26 d). Half-lives were unrelated to physical or demographic characteristics such as body mass, body fat, racial background or age in these relatively homogeneous groups. Carotenoids decreased by similar first-order mechanisms, although the rates differed for individual carotenoids.  (+info)

Antioxidant status and acute malaria in children in Kampala, Uganda. (61/470)

Although antioxidant status has been implicated in the pathogenesis of malaria, these factors need further characterization. A longitudinal study was conducted involving 273 children 1-10 years of age with acute, uncomplicated malaria in Kampala, Uganda. Plasma vitamin A, carotenoids, and vitamin E were measured at enrollment and on day 7. Malaria parasitemia was measured at enrollment, on day 3, and on day 7. Malaria parasitemia had completely cleared in 57.1% and 85.3% of children by day 3 and day 7, respectively. Plasma vitamin A, alpha-carotene, beta-carotene, lycopene, lutein/zeaxanthin, and vitamin E were depressed at enrollment and increased by day 7. Multivariate analyses showed that higher plasma lycopene concentrations at enrollment were associated with clearance of parasitemia between enrollment and day 3 (odds ratio = 1.46, 95% confidence interval = 1.07-2.06, per 0.10 micromol/L of lycopene). This study suggests that children with acute malaria have depressed plasma concentrations of antioxidants, and that higher plasma lycopene is associated with more rapid clearance of malaria parasitemia.  (+info)

Characterization of photosynthetic pigment composition, photosystem II photochemistry and thermal energy dissipation during leaf senescence of wheat plants grown in the field. (62/470)

Photosynthetic pigment composition and photosystem II (PSII) photochemistry were characterized during the flag leaf senescence of wheat plants grown in the field. During leaf senescence, neoxanthin and beta-carotene decreased concomitantly with chlorophyll, whereas lutein and xanthophyll cycle pigments were less affected, leading to increases in lutein/chlorophyll and xanthophyll cycle pigments/chlorophyll ratios. The chlorophyll a/b ratio also increased. With the progression of senescence, the maximal efficiency of PSII photochemistry decreased only slightly in the early morning (low light conditions), but substantially at midday (high light conditions). Actual PSII efficiency, photochemical quenching and the efficiency of excitation capture by open PSII centres decreased significantly both early in the morning and at midday and such decreases were much greater at midday than in the early morning. At the same time, non-photochemical quenching, zeaxanthin and antheraxanthin contents at the expense of violaxanthin increased both early in the morning and at midday, with a greater increase at midday. The results in the present study suggest that a down-regulation of PSII occurred in senescent leaves and that the xanthophyll cycle plays a role in the protection of PSII from photoinhibitory damage in senescent leaves by dissipating excess excitation energy, particularly when exposed to high light.  (+info)

Carotenoids are degraded by free radicals but do not affect lipid peroxidation in unilamellar liposomes under different oxygen tensions. (63/470)

It has been questioned whether carotenoids can act as antioxidants in biological membranes. Biological membranes can be modeled for studies of lipid peroxidation using unilamellar liposomes. Both carotenoid depletion and lipid peroxidation were increased with increasing oxygen tension in unilamellar liposomes. Carotenoids in such liposomes were found to be very sensitive to degradation by free radicals generated from iron and 2,2'-azobis(2-amidinopropane) dihydrochloride, but they were not protective against lipid peroxidation. Lycopene and beta-carotene were more sensitive to free radical attack than lutein, zeaxanthin, and beta-cryptoxanthin.  (+info)

Effect of follicular fluid and oestradiol on the luteinization of rat granulosa cells in vitro. (64/470)

The effect of pig follicular fluid (FF), total or oestrogen-free, and of oestradiol-17 beta on the luteinization and progesterone secretion of rat granulosa cells was investigated during 4 days in culture. Both FF and oestrogen-free FF modified the differentiation of the granulosa cells, particularly their size and the appearance of their nucleoli. Addition of total FF or oestradiol-17 beta (50, 100 or 500 ng/ml) to the control medium markedly increased the progesterone secretion of the granulosa cells, but oestrogen-free FF and dialysed fetal calf serum had no effect. It was concluded that (1) FF could modify the morphological changes of the rat granulosa cells in vitro, but could not inhibit their secretion of progesterone, (2) the granulosa cells were able to synthesize progesterone regardless of their stage of differentiation, (3) oestradiol 17 beta had a direct stimulatory effect on progesterone secretion by granulosa cells in vitro. The possible mode of action of FF upon luteinization is discussed.  (+info)