Field-induced alignment of a smectic-Aphase: A time-resolved x-ray diffraction investigation

The field-induced alignment of a smectic-A phase is, in principle, a complicated process involving the director rotation via the interaction with the field and the layer rotation via the molecular interactions. Time-resolved nuclear magnetic resonance spectroscopy has revealed this complexity in the case of the director alignment, but provides no direct information on the motion of the layers. Here we describe a time-resolved x-ray diffraction experiment using synchrotron radiation to solve the challenging problem of capturing the diffraction pattern on a time scale which is fast in comparison with that for the alignment of the smectic layers. We have investigated the alignment of the smectic-A phase of 4-octyl-4(')-cyanobiphenyl by a magnetic field. The experiment consists of creating a monodomain sample of the smectic-A phase by slow cooling from the nematic phase in a magnetic field with a flux density of 7 T. The sample is then turned quickly through an angle phi(0) about an axis parallel to the x-ray beam direction but orthogonal to the field. A sequence of two-dimensional small angle x-ray diffraction patterns are then collected at short time intervals. Experiments were carried out for different values of phi(0), and at different temperatures. The results show that the alignment behavior changes fundamentally when phi(0) exceeds 45 degrees, and that there is a sharp change in the alignment process when the temperature is less than 3 degrees C below the smectic-A-nematic transition. The results of the x-ray experiments are in broad agreement with the NMR results, but reveal major phenomena concerning the maintenance of the integrity of the smectic-A layer structure during the alignment process.

Phenotype and genotype correlations in two best families

OBJECTIVE

To evaluate mutations in the Best mascular dystrophy (VMD2) gene in two families with Best disease and to describe the phenotype-genotype correlations of genetically determined affected and unaffected individuals.

DESIGN

Family genetic study.

PARTICIPANTS

Two families with Best disease were identified, and family members were evaluated by ophthalmologic examination or fundus photography to assess their phenotype. All affected patients and some of the unaffected family members had a blood sample drawn, and the DNA was analyzed for mutations in the VMD2 gene.

MAIN OUTCOME MEASURES

Twenty-one subjects in the two pedigrees with Best disease were studied. One amino acid-changing mutation in the VMD2 gene was found to segregate independently in each family (P297S or E300D, respectively).

RESULTS

Eleven individuals had some evidence of maculopathy, including retinal pigment epithelial changes, drusen, pigment epithelial irregularities, or cicatricial changes. Ten of these 11 patients (91%) with maculopathy had a mutation in the VMD2 gene, of whom 8 were clinically diagnosed as having Best disease and 2 were diagnosed as having possible Best maculopathy. The one patient without a mutation in the VMD2 gene had age-related macular degeneration (AMD). Ten family members did not have evidence of maculopathy, of whom 6 had no mutation in the VMD2 gene. Four family members (2 in each pedigree) had mutations in the VMD2 gene, abnormal electro-oculogram (EOG) results, but normal maculae at age 40 or older. Of the 7 individuals with no mutation in the VMD2 gene, 6 were phenotypically normal and the other had late-onset visual loss resulting from AMD.

CONCLUSIONS

All family members with maculopathy consistent with Best disease (n = 10) had an amino acid-changing mutation in the VMD2 gene. Four individuals who did not have maculopathy, but did have an abnormal EOG, also had mutations in the VMD2 gene. The presence of a VMD2 mutation is associated with abnormal retinal function, which can occur in the absence of phenotypic manifestation of macular disease.

A prospective study of the relationship between body mass index and cataract extraction among US women and men

BACKGROUND

Obesity may influence several physiologic processes involved in cataract formation such as oxidative stress, glycosylation and osmotic stress.

OBJECTIVE

To examine the association between increased body mass index (BMI) and the incidence of cataract extraction.

DESIGN AND SETTING

The Nurses' Health Study and the Health Professionals Follow-up Study, both prospective cohort studies of US women and men.

SUBJECTS

A total of 87 682 women and 45 549 men aged 45 y and older who did not have diagnosed cataract or cancer at baseline (1980 for women, 1986 for men).

MEASUREMENTS

Cataract extractions occurring between baseline and 1996, confirmed by medical records.

RESULTS

During 16 y of follow-up in the women, and 10 y in the men, (1 097 997 person-y), 4430 incident cases were documented. Compared to participants with BMI less than 23 kg/m(2), those with BMI greater than or equal to 30 kg/m(2) had 36% higher risk of any type of cataract (pooled multivariate relative risk (RR), 1.36; 95% CI, 1.23-1.49) after adjusting for smoking, age and lutein/zeaxanthin intake. The association was strongest for posterior subcapsular (PSC) cataract (pooled multivariate RR, 1.99; 95% CI, 1.55-2.55). With adjustment for diabetes, the RR of obesity associated with posterior subcapsular cataract was 1.68 (95% CI, 1.30-2.17). Obesity was not significantly associated with nuclear cataract.

CONCLUSION

Obesity increases the risk of developing cataract overall, and of PSC cataract in particular; the etiology of PSC cataract may be mediated at least in part by glucose intolerance and insulin resistance, even in the absence of clinical diabetes.

MHC class II genes in European wolves: a comparison with dogs

The genome of the grey wolf, one of the most widely distributed land mammal species, has been subjected to both stochastic factors, including biogeographical subdivision and population fragmentation, and strong selection during the domestication of the dog. To explore the effects of drift and selection on the partitioning of MHC variation in the diversification of species, we present nine DQA, 10 DQB, and 17 DRB1 sequences of the second exon for European wolves and compare them with sequences of North American wolves and dogs. The relatively large number of class II alleles present in both European and North American wolves attests to their large historical population sizes, yet there are few alleles shared between these regions at DQB and DRB1. Similarly, the dog has an extensive array of class II MHC alleles, a consequence of a genetically diverse origin, but allelic overlap with wolves only at DQA. Although we might expect a progression from shared alleles to shared allelic lineages during differentiation, the partitioning of diversity between wolves and dogs at DQB and DRB1 differs from that at DQA. Furthermore, an extensive region of nucleotide sequence shared between DRB1 and DQB alleles and a shared motif suggests intergenic recombination may have contributed to MHC diversity in the Canidae.

History-dependent rheology of a surfactant hexagonal phase

The time-dependent response of a surfactant hexagonal phase of a sodium dodecyl sulphate/pentanol/cyclohexane/brine system to stepped strain is investigated. The dynamics of the system is found to be governed by strain- and noise-induced yielding of the domains of the system. The effects of the applied strain magnitude and the ionic strength of the brine on the character of the transitions experienced by the system are reported.

Evaluation of the ELOVL4 gene in patients with age-related macular degeneration

Stargardt-like macular degeneration (STGD(3)) and autosomal dominant macular degeneration (adMD) share phenotypic characters with atrophic age-related macular degeneration (AMD). Mutations in a photoreceptor cell-specific factor involved in the elongation of very long chain fatty acids (ELOVL(4)) were shown to be associated with STGD(3), adMD, and pattern dystrophy. We screened 778 patients with AMD and 551 age-matched controls to define the role of sequence variants in the ELOVL(4) gene in age-related macular degeneration. We detected three sequence variants in the non-coding region and eight variants in the coding region. No statistically significant association was observed between sequence variants in the ELOVL(4) gene and susceptibility to AMD. However, for the detection of modest effects of multiple alleles in a complex disease, the analysis of larger cohorts of patients may be required.

Assessment of mutations in the Best macular dystrophy (VMD2) gene in patients with adult-onset foveomacular vitelliform dystrophy, age-related maculopathy, and bull's-eye maculopathy

PURPOSE

To study the presence of Best macular dystrophy (VMD2) gene mutations in patients diagnosed with maculopathies other than classic Best disease and to describe the clinical characteristics of these subjects.

DESIGN

Case-comparison study of phenotype-genotype correlations.

METHODS

Patients with either age-related maculopathy (ARM; n = 259) or maculopathies other than classic Best disease (n = 28) were screened for mutations in the Best gene (VMD2; OMIM 153700). These cases were compared with ethnically similar subjects in the same age range without maculopathy (n = 196). All patients underwent a complete dilated ocular examination, and all affected individuals underwent fundus photography. Phenotype-genotype comparisons were made.

MAIN OUTCOME MEASURES

Presence of mutations in the Best gene (VMD2; OMIM 153700) and the clinical phenotype.

RESULTS

Three of 259 patients (1%) with ARM and 2 of 28 patients (7%) with other maculopathies including 1 of 3 patients with adult-onset foveomacular vitelliform dystrophy and 1 of 5 patients with a bull's eye maculopathy, but none of the controls, were found to possess amino acid-changing variants in the VMD2 gene. These included a man with confluent drusen and retinal pigment epithelial detachments (variant in exon 6; T216I), a man with geographic atrophy and numerous soft drusen (variant in exon 10; L567F), a woman with drusen and retinal pigment epithelial alterations (variant in exon 10; L567F), a woman with drusen and retinal pigment epithelial alterations resembling bull's-eye maculopathy (variant in exon 4; E119Q), and a woman diagnosed with adult-onset foveomacular vitelliform dystrophy (variant in exon 4; A146K).

CONCLUSIONS

Novel mutations in the VMD2 gene were found in patients diagnosed with maculopathies other than classic Best disease. Some cases diagnosed as adult-onset vitelliform foveomacular dystrophy may represent a variant of Best disease with delayed onset. The VMD2 gene does not play a major role in the development of ARM.

DNA footprints of European hedgehogs, Erinaceus europaeus and E. concolor: Pleistocene refugia, postglacial expansion and colonization routes

European hedgehogs, Erinaceus europaeus and E. concolor, are among the many European plant and animal taxa that have been subjected to cyclical restriction to glacial refugia and interglacial expansion. An analysis of 95 mitotypes, comprising partial cytochrome b and control region sequences, shows deep divergence between the two hedgehog species. Three europaeus and two concolor clades are clearly identified and are consistent with previously identified refugia for Europe: the Iberian peninsula, Italy, and the Balkans. The degree of mitochondrial divergence among these clades suggests pre-Pleistocene separation of the refugial populations. In contrast, analysis of two nuclear introns clearly separates the two concolor clades, as in the mitochondrial data, but cannot discriminate the three europaeus clades. This discrepancy between nuclear and mitochondrial data is attributed to historical differences in the refugial population size of europaeus and concolor. The geographical distribution of mitotypes is analysed using nested clade analysis. This method, by including unobserved ('missing') mitotypes, can identify mitotype groupings that remain undetected in conventional analyses. However, the application of nested clade analysis to the study of refugial populations may be hampered by such factors as the loss of haplotypes from the refugial areas by repeated contractions of the population and the recent time scale of colonization relative to mutation rate.

Dietary fat and risk for advanced age-related macular degeneration

OBJECTIVE

To evaluate the relationship between intake of total and specific types of fat and risk for advanced age-related macular degeneration (AMD), the leading cause of irreversible blindness in adults.

DESIGN

A multicenter eye disease case-control study.

SETTING

Five US clinical ophthalmology centers.

PATIENTS

Case subjects included 349 individuals (age range, 55-80 years) with the advanced, neovascular stage of AMD diagnosed within 1 year of their enrollment into the study who resided near a participating clinical center. Control subjects included 504 individuals without AMD but with other ocular diseases. Controls were from the same geographic areas as cases and were frequency-matched to cases by age and sex.

MAIN OUTCOME MEASURES

Relative risk for AMD according to level of fat intake, controlling for cigarette smoking and other risk factors.

RESULTS

Higher vegetable fat consumption was associated with an elevated risk for AMD. After adjusting for age, sex, education, cigarette smoking, and other risk factors, the odds ratio (OR) was 2.22 (95% confidence interval [CI], 1.32-3.74) for persons in the highest vs those in the lowest quintiles of intake (P for trend,.007). The risk for AMD was also significantly elevated for the highest vs lowest quintiles of intake of monounsaturated (OR, 1.71) and polyunsaturated (OR, 1.86) fats (Ps for trend,.03 and.03, respectively). Higher consumption of linoleic acid was also associated with a higher risk for AMD (P for trend,.02). Higher intake of omega-3 fatty acids was associated with a lower risk for AMD among individuals consuming diets low in linoleic acid, an omega-6 fatty acid (P for trend,.05; P for continuous variable,.03). Similarly, higher frequency of fish intake tended to reduce risk for AMD when the diet was low in linoleic acid (P for trend,.05). Conversely, neither omega-3 fatty acids nor fish intake were related to risk for AMD among people with high levels of linoleic acid intake.

CONCLUSION

Higher intake of specific types of fat--including vegetable, monounsaturated, and polyunsaturated fats and linoleic acid--rather than total fat intake may be associated with a greater risk for advanced AMD. Diets high in omega-3 fatty acids and fish were inversely associated with risk for AMD when intake of linoleic acid was low.

Prospective study of zinc intake and the risk of age-related macular degeneration

PURPOSE

Zinc is found in high concentrations in the retina and is hypothesized to reduce the risk of age-related macular degeneration (AMD). Any long-term benefit associated with dietary zinc intake has not been evaluated.

METHODS

We followed 66,572 women and 37,636 men who were > or = 50 years old and had no diagnosis of AMD or cancer. Zinc intake from food, multivitamins, and supplements was assessed with a semiquantitative food-frequency questionnaire at baseline (in 1984 for women and in 1986 for men) and repeated during follow-up (twice for women, once for men).

RESULTS

During 10 years of follow-up for women and 8 years of follow-up for men, we confirmed 384 incident cases of AMD (195 cases of the early form and 189 cases of the late form) associated with a visual acuity loss of 20/30 or worse. After multivariate adjustment for potential risk factors, the pooled relative risk was 1.13 (95% confidence interval [CI], 0.82 to 1.57; p-value, test for trend, 0.74) among participants in the highest quintile of total zinc intake (energy-adjusted median; 25.5 mg/day for women and 40.1 mg/day for men) compared with those in the lowest quintile (energy-adjusted median; 8.5 mg/day for women and 9.9 mg/day for men). The relative risk for highest compared with lowest quintile was 1.04 (95% CI, 0.59 to 1.83; p-value, test for trend, 0.54) for zinc intake from food. Subjects who took zinc supplements had a pooled multivariate relative risk of 1.04 (95% CI, 0.75 to 1.45).

CONCLUSIONS

In these two large prospective studies, moderate zinc intake, either in food or in supplements, was not associated with a reduced risk of AMD.

Prospective study of dietary fat and the risk of age-related macular degeneration

BACKGROUND

The relation between intakes of total fat and specific types of fat and age-related macular degeneration (AMD) remains unclear.

OBJECTIVE

Our objective was to examine prospectively the association between fat intake and AMD.

DESIGN

We conducted a prospective follow-up study of participants in the Nurses' Health Study and the Health Professionals Follow-up Study. At baseline (1984 for women and 1986 for men), the study included 42743 women and 29746 men aged > or = 50 y with no diagnosis of AMD who were followed until 1996. Fat intake was assessed with a food-frequency questionnaire.

RESULTS

We accrued 567 patients with AMD with a visual loss of 20/30 or worse. The pooled multivariate relative risk (RR) for the highest compared with the lowest quintile of total fat intake was 1.54 (95% CI: 1.17, 2.01; P for trend = 0.008). Linolenic acid was positively associated with risk of AMD (top versus bottom quintile of RR: 1.49; 95% CI: 1.15, 1.94; P for trend = 0.0009). Docosahexaenoic acid had a modest inverse relation with AMD (top versus bottom quintile of RR: 0.70; 95% CI: 0.52, 0.93; P for trend = 0.05), and >4 servings of fish/wk was associated with a 35% lower risk of AMD compared with < or = 3 servings/mo (RR: 0.65; 95% CI: 0.46, 0.91; P for trend = 0.009).

CONCLUSIONS

Total fat intake was positively associated with risk of AMD, which may have been due to intakes of individual fatty acids, such as linolenic acid, rather than to total fat intakes per se. A high intake of fish may reduce the risk of AMD.

Evaluating the effectiveness of a vision rehabilitation intervention using an objective and subjective measure of functional performance

PURPOSE

To test the hypothesis that vision rehabilitation using optometry, occupational therapy and social work services increases patients' functional ability and to assess whether involving families in the intervention results in more successful outcomes.

METHODS

We conducted an outcome study of 97 patients new to the Vision Rehabilitation Service. Subjects were between the ages of 19 and 91 years, with a median age of 76. Their visual acuities were 20/100 or worse in the better eye, with 50% of the subjects having acuities worse than 20/200. Macular degeneration was the most prevalent diagnosis. Subjects were assigned to either an individually focused (n=48) or a family focused (n=49) intervention. The outcome measure was change in function, as assessed by speed and accuracy of performance (objective measure) and by the patients' self-reports of difficulty and dependency in performing daily activities (subjective measures). Data were collected before and after the intervention.

RESULTS

Most patients had documented improvement after rehabilitation on both objective (p=.0001) and subjective (decreased dependency, p=.01) measures of function. The sample size did not provide adequate statistical power to show differences between family focused and individually focused interventions.

CONCLUSIONS

This study documents significant improvement after vision rehabilitation for a predominantly elderly population. Patients in both family and individually focused interventions improved comparably.

Age-related eye diseases: impact of hormone replacement therapy, and reproductive and other risk factors

In Western countries, age-related macular degeneration is the leading cause of legal blindness in the population over 60 years of age, and cataract is the leading cause of visual impairment worldwide. Because postmenopausal women are living longer, they have a greater probability of developing a variety of age-related visual disorders. As the population ages, the physical and emotional toll of these ailments, as well as the burden on the health care system, will escalate. Currently, interventional therapy for age-related macular degeneration is limited to a small subpopulation of patients who can benefit from laser treatment, whereas surgery is the only effective treatment for cataract. The need for other therapeutic options and preventive measures remains a major challenge for the future. Studies among women have suggested that exposure to estrogens is associated with a reduction in risk of developing ocular diseases associated with aging. This article addresses the epidemiology of age-related macular degeneration and cataract, focusing on the specific risks for women, and discusses factors that may influence development or progression of these visual disorders.

A prospective study of alcohol consumption and cataract extraction among U.S. women

PURPOSE

Alcohol consumption has been implicated in the pathogenesis of cataract in some, but not all analytic studies. To date, no prospective analysis of the relationship between alcohol consumption and cataract has been conducted in women.

METHODS

We examined the association between alcohol consumption and cataract extraction in a prospective cohort of female registered nurses. In 1980, 50,461 women were included and others were added as they became 45 years of age for a total of 77,466 women. Information on alcohol consumption and incidence of senile cataract extraction was ascertained during 12 years of follow-up with biennial questionnaires.

RESULTS

We observed 1468 cases of cataract extraction in 761,036 person-years of follow-up. Compared to nondrinkers, those consuming alcohol were not at increased risk of cataract, even up to 25 grams or more per day (2 or more drinks). Results remained unchanged after controlling for cataract risk factors including cigarette smoking, body mass index, and diabetes. When risk was examined for specific cataract subtypes only, those in the highest category of consumption had a multivariate relative risk of 1.10 for nuclear cataracts and 1.50 for posterior subcapsular cataracts only.

CONCLUSIONS

These prospective data suggest that there is no substantial overall increased risk of senile cataract due to alcohol intake. The possibility that alcohol consumption leads to a modest increased risk of posterior subcapsular type opacities requiring extraction merits further exploration.

Patterns of tumor initiation in choroidal melanoma

This study attempts to document the occurrence of tumors with respect to clock hour location and distance from the macula and to evaluate tumor location in relation to retinal topography and light dose distribution on the retinal sphere. Analysis of patterns of tumor initiation may provide new evidence to clarify the controversy regarding the possible light-related etiology of choroidal melanoma. Incident cases of choroidal and ciliary body melanoma in Massachusetts residents diagnosed between 1984 and 1993 were the basis for analysis. Conventional fundus drawings and photos were used to assess the initiation site of each tumor. The initiation site was defined as the intersect between the largest tumor diameter and the largest perpendicular diameter of the tumor. Initiation sites were recorded using spherical coordinates. The retinal sphere was divided into 61 mutually exclusive sectors defined according to clock hour and anteroposterior distance from the macula. Rates of initiation were computed for each sector, overall, and according to gender and other clinical factors. Results were similar in left and right eyes; therefore, these were combined in analysis. Tumor initiation had a predilection for the macula (P < 0.0001). Overall, no significant clock hour preference was observed (P = 0.63). However, the parafoveal zone showed a strong circular trend (P < 0.01), with highest rates occurring in the temporal region, and the lowest rates occurring in the nasal region. Rates of occurrence in six progressively more anterior concentric zones (designated as the foveal, parafoveal, posterior, peripheral, anterior, and ciliary body zones) were 21.4, 14.2, 12.1, 8.9, 4.5, and 4.3 counts per spherical unit per 1000 eyes, respectively. Concentric zone location did not vary by gender (P = 0.93) or laterality (P = 0.78). However, posterior location was associated with light iris color (P = 0.01). Tumor diameters were largest in the peripheral region of the fundus and smallest in the macular and ciliary body zone (P < 0.001). Clock hour location was not influenced by gender (P = 0.74), laterality (P = 0.53), iris color (P = 0.84), or tumor diameter (P = 0.73). Results suggest that tumor initiation is not uniformly distributed, with rates of occurrence concentrated in the macular area and decreasing monotonically with distance from the macula to the ciliary body. This pattern is consistent with the retinal topography and correlates positively with the dose distribution of solar light on the retinal sphere.

A randomized controlled trial of varying radiation doses in the treatment of choroidal melanoma

OBJECTIVE

To determine if a reduction in proton radiation dose from the standard dose of 70 cobalt gray equivalents (CGE) to 50 CGE would decrease radiation-induced complications, thereby improving visual prognosis, without compromising local tumor control for patients with uveal melanoma at high risk of these complications.

DESIGN

Randomized, double-masked clinical trial.

PARTICIPANTS

A total of 188 patients with small or medium-sized choroidal melanomas (<15 mm in diameter and <5 mm in height) near the optic disc or macula (within 4 disc diameters of either structure).

METHODS

Patients were treated with proton beam therapy at doses of either 50 CGE or 70 CGE between October 1989 and July 1994, and followed up biannually through April 1998. Outcomes included visual acuity, radiation complications, melanoma recurrence, and metastasis.

RESULTS

Proportions of patients retaining visual acuity of at least 20/200 were similar in the 2 dose groups at 5 years after radiation (approximately 55%). Similar numbers of patients in each group experienced tumor regrowth (2 patients at 50 CGE vs 3 patients at 70 CGE; P>.99) and metastasis (7 patients at 50 CGE vs 8 patients at 70 CGE;P=.79). Five-year rates of radiation maculopathy also were similar (for both groups, approximately 75% for tumors within 1 disc diameter and 40% for tumors >1 disc diameter from the macula). Rates of radiation papillopathy were nonsignificantly decreased in the 50-CGE treatment group when tumors were located 1 disc diameter or less from the optic disc (P=.20). Patients treated with the lower dose also experienced significantly less visual field loss.

CONCLUSIONS

This level of dose reduction did not result in a lesser degree of visual acuity loss. The lower-dose group did experience significantly less visual field loss. Local tumor recurrence and metastatic death rates were similar in both dose groups. Arch Ophthalmol. 2000;118:773-778

Evolutionary lineages of RT1.Ba in the Australian Rattus

In this study, the evolutionary history of the variable second exon of RT1.Ba and its adjoining intron b are compared across a number of species and subspecies of the Australian RATTUS: Three lineages are identified in the second intron across a range of Rattus species. Two of these lineages, separated by the insertion of a probable rodent short interspersed nucleotide element and by point mutations outside the indel region, are both found in each of the major clades of the endemic Australian RATTUS: This pattern of ancestral polymorphism is reflected in the adjoining exon 2 sequences, although phylogenetic constraints confirm that the clustering is not identical to that of the associated intron sequences. In addition, the coding sequences show evidence of the retention of ancestral polymorphism, with identical exon sequences found in two divergent species, and some indication of gene conversion detected for the exon sequences.

Prospective study of alcohol consumption and the risk of age-related macular degeneration

OBJECTIVE

To describe the relationship between alcohol consumption and the incidence of age-related macular degeneration (AMD).

METHODS

We conducted a prospective study among female nurses between 1980 and 1994 and among male health professionals between 1986 and 1994. We included 32764 women and 29488 men who were 50 years or older, without a diagnosis of AMD or cancer at baseline, and added additional subjects to the analysis as they reached 50 years of age. Their alcohol intake was assessed at baseline and updated during follow-up evaluations using a validated semiquantitative food-frequency questionnaire. After separate analyses for women and men, pooled estimates of the relationship of alcohol to the risk of AMD were calculated.

RESULTS

Age-related macular degeneration associated with a visual acuity loss of 20/30 or worse, including the early and dry and wet types, was diagnosed in 298 women (from 697498 person-years of follow-up) and 153 men (229 180 person-years) by 1994, the end of follow-up. After controlling for age, smoking, and other risk factors, the pooled relative risks (RRs) and 95% confidence intervals (CIs) for AMD compared with nondrinkers were 1.0 (0.7-1.2) for drinkers who consumed 0.1 to 4.9 g/d of alcohol; 0.9 (0.6-1.4) for 5 to 14.9 g/d; 1.1 (0.7-1.7) for 15 to 29.9 g/d; and 1.3 (0.9-1.8) for 30 g/d or more. Among women, there was a suggestion of a modest increased risk of the disease in drinkers who consumed 30 g/d or more (RR, 1.5; 95% CI, 1.0-2.4); this was limited to an increased risk of the early and dry form (RR, 2.0; 95% CI, 1.2-3.4). No specific type of alcohol provided protection against AMD.

CONCLUSION

This prospective study does not support an inverse relationship between moderate alcohol consumption and risk of AMD.

Variation on islands: major histocompatibility complex (Mhc) polymorphism in populations of the Australian bush rat

Loss of genetic variation in small, isolated populations is commonly observed at neutral or nearly neutral loci. In this study, the loss of genetic variation was assessed in island populations for a locus of major histocompatibility complex (Mhc), a locus shown to be under the influence of balancing selection. A total of 36 alleles was found at the second exon of RT1.Ba in 14 island and two mainland populations of Rattus fuscipes greyii. Despite this high overall diversity, a substantial lack of variation was observed in the small island populations, with 13 islands supporting only one to two alleles. Two populations, Waldegrave and Williams Islands, showed moderately high levels of heterozygosity (52-56%) which were greater than expected under neutrality, suggesting the action of balancing selection. However, congruence between the level of variation at this Mhc locus and in previous allozyme electrophoresis and mitochondrial DNA studies highlights the dominant influence of genetic drift and population factors, such as bottlenecks and structuring in the founding population, in the loss of genetic variation in these small, isolated populations.

The genetics of age-related macular degeneration

Age-related macular degeneration (AMD) is increasingly recognized as a complex genetic disorder in which one or more genes contribute to an individual's susceptibility for developing the condition. Twin and family studies as well as population-based genetic epidemiologic methods have convincingly demonstrated the importance of genetics in AMD, though the extent of heritability, the number of genes involved, and the phenotypic and genetic heterogeneity of the condition remain unresolved. The extent to which other hereditary macular dystrophies such as Stargardts disease, familial radial drusen (malattia leventinese), Best's disease, and peripherin/RDS-related dystrophy are related to AMD remains unclear. Alzheimer's disease, another late onset, heterogeneous degenerative disorder of the central nervous system, offers a valuable model for identifying the issues that confront AMD genetics.

A prospective study of vitamin supplement intake and cataract extraction among U.S. women

We prospectively examined the association between vitamin supplement intake and the incidence of cataract extraction during 12 years of follow-up in a cohort of 47,152 female nurses. Women were 45 years or older and free of diagnosed cancer in 1980; others were added as they reached 45 years of age, for a total of 73,956 women. During 720,082 years of follow-up, 1,377 senile cataracts were diagnosed and extracted. Those who used multivitamins or separate supplements of vitamin C, E, or A did not have decreased risks of cataract as compared with nonusers even for use of 10 or more years. After adjusting for cataract risk factors, including cigarette smoking, body mass index, and diabetes mellitus, users of vitamin C supplements for 10 or more years had a relative risk (RR) of 0.95 [95% confidence interval (CI) = 0.76-1.20]. Associations were stronger among long-term vitamin C supplement users who were never-smokers (RR = 0.71; 95% CI = 0.47-1.08) and less than 60 years of age (RR = 0.72; 95% CI = 0.49-1.04). These findings suggest that there is little overall benefit of long-term use of vitamin supplements for risk of cataracts requiring extraction.

A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women

BACKGROUND

Oxidation of lens proteins plays a central role in the formation of age-related cataracts, suggesting that dietary antioxidants may play a role in prevention. However, the relation between specific antioxidants and risk of cataract remains uncertain.

OBJECTIVE

Our objective was to examine prospectively the association between carotenoid and vitamin A intakes and cataract extraction in women.

METHODS

A prospective cohort of registered female nurses aged 45-71 y and free of diagnosed cancer was followed; in 1980, 50461 were included and others were added as they became 45 y of age for a total of 77466. Information on nutrient intake was assessed by repeated administration of a food-frequency questionnaire during 12 y of follow-up.

RESULTS

During 761762 person-years of follow-up, 1471 cataracts were extracted. After age, smoking, and other potential cataract risk factors were controlled for, those with the highest intake of lutein and zeaxanthin had a 22% decreased risk of cataract extraction compared with those in the lowest quintile (relative risk: 0.78; 95% CI: 0.63, 0.95; P for trend = 0.04). Other carotenoids (alpha-carotene, beta-carotene, lycopene, and beta-cryptoxanthin), vitamin A, and retinol were not associated with cataract in multivariate analysis. Increasing frequency of intakes of spinach and kale, foods rich in lutein, was associated with a moderate decrease in risk of cataract.

CONCLUSIONS

Lutein and zeaxanthin and foods rich in these carotenoids may decrease the risk of cataracts severe enough to require extraction.

A prospective study of carotenoid intake and risk of cataract extraction in US men

BACKGROUND

Dietary antioxidants, including carotenoids, are hypothesized to decrease the risk of age-related cataracts by preventing oxidation of proteins or lipids within the lens. However, prospective epidemiologic data concerning this phenomenon are limited.

OBJECTIVE

Our objective was to examine prospectively the association between carotenoid and vitamin A intakes and cataract extraction in men.

DESIGN

US male health professionals (n = 36644) who were 45-75 y of age in 1986 were included in this prospective cohort study. Others were subsequently included as they became 45 y of age. A detailed dietary questionnaire was used to assess intake of carotenoids and other nutrients. During 8 y of follow-up, 840 cases of senile cataract extraction were documented.

RESULTS

We observed a modestly lower risk of cataract extraction in men with higher intakes of lutein and zeaxanthin but not of other carotenoids (alpha-carotene, beta-carotene, lycopene, and beta-cryptoxanthin) or vitamin A after other potential risk factors, including age and smoking, were controlled for. Men in the highest fifth of lutein and zeaxanthin intake had a 19% lower risk of cataract relative to men in the lowest fifth (relative risk: 0.81; 95% CI: 0.65, 1.01; P for trend = 0.03). Among specific foods high in carotenoids, broccoli and spinach were most consistently associated with a lower risk of cataract.

CONCLUSIONS

Lutein and zeaxanthin may decrease the risk of cataracts severe enough to require extraction, although this relation appears modest in magnitude. The present findings add support for recommendations to consume vegetables and fruit high in carotenoids daily.

Influence of age-related maculopathy on visual functioning and health-related quality of life

PURPOSE

To describe the influence of age-related maculopathy on visual functioning and health-related quality of life.

METHODS

A prospective, cross-sectional, observational cohort sample of 201 persons with various stages of age-related maculopathy was recruited from the Massachusetts Eye and Ear Infirmary as part of a longitudinal study of age-related macular degeneration. Persons were considered to have age-related maculopathy if one or more of the following clinical characteristics were present: drusen, retinal pigment epithelial changes, geographic atrophy, or evidence of exudative disease. Median corrected visual acuity for this sample was 20/25 in the better eye, with all subjects having 20/200 or better visual acuity in at least one eye at baseline. All participants underwent a comprehensive ophthalmologic examination with a dilated pupil. In addition to the usual clinical data collection, severity of age-related maculopathy was graded by an ophthalmologist who used standard clinical criteria and was masked to the participants' descriptions of visual functioning and health-related quality of life. All participants completed an interview that included the Activities of Daily Vision Scale, a survey designed to assess difficulties with routine daily activities that require vision, and the Short Form-36 Health Survey, a generic measure of multidimensional health-related quality of life.

RESULTS

Severity of age-related maculopathy was associated with poorer scores of the Activities of Daily Vision Scale. This association was most significant for near vision and driving activities. In this sample, the SF-36 Health Survey scales were not significantly correlated with severity of age-related maculopathy.

CONCLUSIONS

Reported visual functioning is significantly associated with the clinical severity of age-related maculopathy. However, once visual acuity is taken into consideration, clinical grading of age-related maculopathy did not explain a significant portion of the variation in visual functioning. The lack of significant correlation between severity of age-related maculopathy and the SF-36 Health Survey may have resulted from the small number of participants in our sample with severe bilateral age-related maculopathy.