Biomedical subjects

Line Kessel

Publications and source records attributed to Line Kessel.

11 recordsLinked to original sources

PubMed2006

Early lens aging is accelerated in subjects with a high risk of ischemic heart disease: an epidemiologic study.

BACKGROUND: Ischemic heart disease (IHD) is one of the most important causes of mortality and morbidity in the Western world. There is a relationship between aging of the lens of the human eye and cardiovascular disease. The present study was conducted to examine if the risk of ischemic heart disease could be estimated by fluorophotometric assessment of lens aging. METHODS: A total of 421 subjects were included. Risk of IHD was estimated from non-ocular data using the Precard software. Lens aging was quantified by lens fluorometry. RESULTS: The risk of IHD was strongly related to lens fluorophore accumulation (p = 0.001). The relationship between IHD and lens aging was attributable to tobacco smoking and dysglycemia. CONCLUSION: The risk of ischemic heart disease related to smoking and diabetes mellitus can be estimated using the aging of the lens of the eye as a biomarker for generalized tissue-damage.

Adult↗

PubMed2006

Lens fluorescence in relation to glucose tolerance and genetic predisposition to type 2 diabetes mellitus in a population-based study.

PURPOSE: The fluorescence of the lens has the characteristics of a life-long cumulative index of glycemia, and it is elevated in patients with diabetes in proportion to the duration of diabetes and the level of glycemia. Consequently, lens fluorometry should be capable of providing an estimate of prediagnostic disease duration when patients are diagnosed with type 2 diabetes. Among euglycemic subjects, first-degree relatives of patients with type 2 diabetes tend to have higher glycemia levels than subjects who are unrelated to diabetes patients. They should therefore also have the higher lens fluorescence values. METHODS: The study comprised 218 Caucasian subjects in self-reported good health aged 30-88 years who were recruited from population-based studies to represent approximately equal proportions of different type 2 diabetes family history characteristics: no diabetic relative, first-degree offspring, second-degree offspring, not first-degree offspring but possibly second-degree offspring, or uncertain family history. Characterization of subjects included oral glucose tolerance testing and lens fluorometry. RESULTS: Type 2 diabetes was diagnosed in 10 subjects (4.6% of the population) and impaired glucose tolerance in 12 subjects (5.5%). Regression analysis indicated a prediagnostic duration of type 2 diabetes of 2.7 years versus 0.1 years for impaired glucose tolerance. Neither group demonstrated significantly increased lens fluorescence compared with euglycemic subjects. Being a first-degree relative of a patient with type 2 diabetes was associated with higher lens fluorescence than having no relative with diabetes (p = 0.02). CONCLUSIONS: Population screening by fasting blood glucose measurement can advance the diagnosis and initiation of treatment of type 2 diabetes mellitus by nearly a decade, compared with previous studies of patients diagnosed in routine clinical practice. In addition to higher than normal glycemia, euglycemic subjects who are offspring of patients with type 2 diabetes also have both elevated lens fluorescence and elevated glycemia. Fasting blood glucose measurement remains the method of choice for type 2 diabetes screening.

Adult↗

PubMed2006

Heritability of retinal vessel diameters and blood pressure: a twin study.

PURPOSE: To assess the relative influence of genetic and environmental effects on retinal vessel diameters and blood pressure in healthy adults, as well as the possible genetic connection between these two characteristics. METHODS: In 55 monozygotic and 50 dizygotic same-sex healthy twin pairs, aged 20 to 46 years, interpolated diameter estimates for the central retinal artery (CRAE), the central retinal vein (CRVE), and the artery-to-vein diameter ratio (AVR) were assessed by analysis of digital gray-scale fundus photographs of right eyes. RESULTS: The heritability was 70% (95% CI: 54%-80%) for CRAE, 83% (95% CI: 73%-89%) for CRVE, and 61% (95% CI: 44%-73%) for mean arterial blood pressure (MABP). Retinal artery diameter decreased with increasing age and increasing arterial blood pressure. Mean vessel diameters in the population were 165.8 +/- 14.9 microm for CRAE, 246.2 +/- 17.7 microm for CRVE, and 0.67 +/- 0.05 microm for AVR. No significant influence on artery or vein diameters was found for gender, smoking, body mass index (BMI), total cholesterol, fasting blood glucose, or 2-hour oral glucose tolerance test values. CONCLUSIONS: In healthy young adults with normal blood pressure and blood glucose, variations in retinal blood vessel diameters and blood pressure were predominantly attributable to genetic effects. A genetic influence may have a role in individual susceptibility to hypertension and other vascular diseases. The results suggest that retinal vessel diameters and the possible associated variations in risk of vascular disease are primarily genetic characteristics.

Adult↗

PubMed2005

Impact of UVR-A on whole human lenses, supernatants of buffered human lens homogenates, and purified argpyrimidine and 3-OH-kynurenine.

PURPOSE: Yellow chromophores and fluorescent compounds accumulate in the lens with age. Some of these compounds are photochemically active. The present study aimed to examine the photochemical effect of ultraviolet radiation-A (UVR-A) on the human lens. METHODS: Intact human lenses and supernatants of buffered lens homogenates were exposed to UVR-A. The effect of UVR-A was evaluated by time-resolved and steady-state fluorescence spectroscopy, visual evaluation of colour and protein gel electrophoresis. RESULTS: Intact lenses exposed to UVR-A showed no changes in time-resolved or steady-state fluorescence properties but the yellow coloration was visibly attenuated. The supernatants of buffered lens homogenates exposed to UVR-A demonstrated a reduction in time-resolved and steady-state fluorescent properties and protein cross-linking. CONCLUSIONS: Exposure of the intact lens to UVR-A causes chromophore bleaching without affecting fluorescence, indicating that non-fluorescent chromophores have been destroyed. After homogenization, both chromophores and fluorophores from the lens suffer damage and proteins aggregate. This indicates that powerful mechanisms of protection against UVR-A found in the intact lens are disturbed by homogenization of the lens, suggesting that isolated lens proteins cannot be used as a model system for studying cataractogenesis. Hypothetically, the protective mechanism could be related to the rigidly packed three-dimensional structure of the lens proteins or to the abundance of antioxidative and free radical scavenging defence systems.

Aged↗

PubMed2005

Heritability of cilioretinal arteries: a twin study.

PURPOSE: To determine whether the presence of one or more cilioretinal arteries, a distinct element of the pattern of fundus vessels, is genetically programmed, influenced by environmental factors, or the result of random mechanisms of vascular development. METHODS: The fundi of 112 pairs of healthy monozygotic and dizygotic twins were examined using digital fundus photography and visual assessment of grayscale fundus photographs and color transparencies to detect the presence of cilioretinal arteries. RESULTS: Cilioretinal arteries were present in 45.1% of participants and 28.8% of eyes. The majority of cilioretinal arteries, 88.2%, were located temporally, and 11.8% were located nasally. Monozygotic twins had higher concordance rates for cilioretinal arteries than dizygotic twins. Tetrachoric correlations and Mantel-Haenszel odds ratios demonstrated statistically significant evidence of a genetic effect underlying the presence of cilioretinal arteries (P < 0.01). Statistical analysis supported the hypothesis that additive genetic factors influenced the presence of cilioretinal arteries with a heritability of 71.4%, the remaining variance being attributable to nonshared or random environmental factors. CONCLUSIONS: The presence or absence of one or more cilioretinal arteries in healthy persons is markedly influenced by genetic factors.

Adult↗

PubMed2004

Visual acuity and refractive errors in a suburban Danish population: Inter99 Eye Study.

PURPOSE: The present study was performed as part of an epidemiological study, the Inter99 Eye Study. The aim of the study was to describe refractive errors and visual acuity (VA) in a suburban Danish population. METHODS: The Inter99 Eye Study comprised 970 subjects aged 30-60 years and included a random control group as well as groups at high risk for ischaemic heart disease and diabetes mellitus. The present study presents VAs and refractive data from the control group (n = 502). All subjects completed a detailed questionnaire and underwent a standardized general physical and ophthalmic examination including determination of best corrected VA and subjective refractioning. RESULTS: Visual acuity </= 0.05 was found in one eye of one subject and VA </= 0.3 in 11 eyes of 11 subjects. The main cause of reduced visual function was strabismic amblyopia. Myopia (</= - 0.5 D, spherical equivalent refraction) was present in 33.1% of right eyes of the total population but in 56.8% of subjects with a university degree. CONCLUSIONS: Strabismic amblyopia was a significant cause of unilateral visual impairment. Myopia was approximately twice as frequent in subjects with a university degree as in the remaining study population.

Adult↗

PubMed2003

Corneal fluorescence in relation to genetic and environmental factors: a twin study.

PURPOSE: Corneal fluorescence is believed to be caused by advanced glycation end products formed by non-enzymatic glycation on corneal proteins. The purpose of the present twin study was to examine whether the process is related to genetic or environmental factors. METHODS: Corneal fluorescence was measured in 59 monozygotic and 54 dizygotic twin pairs. The influences of genetic and environmental factors were estimated using structural equation modelling. RESULTS: Interindividual variation in corneal fluorescence was attributable to environmental factors, whereas the effect of genetic factors was of little or no significance. Corneal fluorescence correlated significantly with smoking habits (r = 0.38) and the 2-hour oral glucose tolerance test response (r = 0.27), and increased with age (p < 0.0001). CONCLUSION: Fluorophore accumulation in the cornea was attributable to age and environmental effects, of which smoking was the most conspicuous identifiable factor, although glucose was also of relevance. However, the greater part of interindividual variation in corneal fluorescence remains unexplained.

Adult↗

PubMed2003

Corneal autofluorescence in relation to permeability of the blood-aqueous barrier in diabetic patients with clinically significant macular edema and in an age-matched control group.

PURPOSE: Corneal autofluorescence is related to advanced glycation end products formed by glucose that reaches the cornea via the aqueous humour. The aim of the study was to examine the influence on autofluorescence of changes in permeability of the blood aqueous barrier. METHODS: Corneal autofluorescence was measured in 50 diabetic patients with clinically significant macular edema and in 28 age-matched control subjects. Permeability of the blood aqueous barrier was assessed using the diffusion coefficient of fluorescein. RESULTS: Corneal autofluorescence was higher in diabetic subjects than in the control group, mean (SD) at an excitation wavelength of 458 nm was 41.2 ng f-eq/ml (11.7) in diabetic patients and 26.5 ng f-eq/ml (7.3) in the control group, p < 0.001. The mean permeability of the blood aqueous barrier, Kd(F), was 492.0.10(-6) min(-1 )in the diabetic patients and 484.2. 10(-6) min(-1)in the control group. There was no association between permeability of the blood aqueous barrier and corneal autofluorescence, p = 0.99 for the diabetic patients and p = 0.15 for the control group (458 nm). CONCLUSIONS: Corneal autofluorescence was unaffected by permeability of the blood aqueous barrier suggesting that formation of advanced glycation products is limited by other factors than the concentration of glucose in the aqueous humour, or that other factors unrelated to nonenzymatic glycation of stromal proteins are involved.

Adult↗

PubMed2003

Fluorescein transport through the blood-aqueous and blood-retinal barriers in diabetic macular edema.

PURPOSE: To investigate the integrity of the blood-aqueous barrier (BAB) and the blood-retinal barrier (BRB) in diabetic patients with clinically significant macular edema (CSME). METHODS: The rate constant (Kd(F)) of the BAB and the permeability of the blood-retinal barrier for non-protein bound fluorescein were determined simultaneously by fluorometry. Results were analysed pairwise in diabetic patients (n = 25) with CSME in one eye and without CSME in the other eye. RESULTS: Kd(F) for the eyes with CSME was significantly increased compared to eyes without CSME (444. 10(-6) min( -1) and 387. 10(-6) min(-1) respectively, p = 0.01). The passive permeability of the BRB was also significantly increased in CSME (5.7 nm/sec and 3.5 nm/sec respectively, p = 0.009, n = 19). CONCLUSIONS: Both the rate constant of the BAB and the BRB permeability were significantly increased in CSME indicating that eye-specific factors are common for both barriers in diabetic patients with CSME.

Adult↗

PubMed2003

Evaluation of heredity as a determinant of retinal nerve fiber layer thickness as measured by optical coherence tomography.

PURPOSE: To study to what extent genetic factors determine the retinal nerve fiber layer thickness (RNFLT) in healthy subjects. METHODS: In vivo peripapillary optical coherence tomography (OCT), clinical examination, lens fluorescence, and fundus photography were performed on both eyes of 25 monozygotic and 25 dizygotic same-sex pairs of twins. The cross-sectional study included twins aged from 20 to 45 years recruited from a population-based register. Only healthy eyes were included. MAIN OUTCOME VARIABLES: peripapillary OCT RNFLT, reproducibility, and heritability (the proportion of the total observed variance statistically attributable to genetic factors). RESULTS: The within-pair difference in RNFLT was 4.6% (0.7%-15.2%; median [range]) in monozygotic versus 7.3% (0.2%-20%) in dizygotic twins (P = 0.032, Mann-Whitney test). The RNFLT heritability was 66%. The RNFLT measurement was found to decrease 3.8 microm per decade (P = 0.003). The RNFLT heritability increased to 82%, when corrected for the effect of age and excluding within-pair refractive differences of 2 D or more. The signal-to-noise ratio correlated with lens transmittance (r = 0.25, P = 0.012), age (r = -0.29, P = 0.004), and RNFLT (r = 0.43, P < 0.001). Intravisit RNFLT reproducibility was 4.2%. CONCLUSIONS: Peripapillary RNFLT in healthy adults, as measured by OCT, was determined predominantly by genetic factors in this study population. Theoretically, these factors may involve variations in the number of ganglion cells and nerve fiber formations early in life and/or in the rate at which these structures are subsequently lost.

Adult↗

PubMed2002

Time-resolved and steady-state fluorescence spectroscopic studies of the human lens with comparison to argpyrimidine, pentosidine and 3-OH-kynurenine.

The intrinsic fluorescence from the human lens on excitation in the UV region, referred to as blue lens autofluorescence, increases with age or in the presence of diabetes. The present study reveals that the relative contribution of compounds responsible for the blue autofluorescence appears to be a constant with age. Three potential candidates for the blue fluorescence were also studied with respect to fluorescence spectroscopic properties. These were argpyrimidine and pentosidine, both advanced glycation end products, and 3-hydroxykynurenine (3-OH-kynurenine), a photooxidative derivative of tryptophan. It was shown that the spectral properties of argpyrimidine and pentosidine are compatible with the observed blue fluorescence of the human lens, whereas the fluorescence from 3-OH-kynurenine is negligible.

Adult↗