Surface roughness after excimer laser ablation using a PMMA model: profilometry and effects on vision

PURPOSE: To show that the limited quality of surfaces produced by one model of excimer laser systems can degrade visual performance with a polymethylmethacrylate (PMMA) model. METHODS: A range of lenses of different powers was ablated in PMMA sheets using five DOS-based Nidek EC-5000 laser systems (Nidek Technologies, Gamagori, Japan) from different clinics. Surface quality was objectively assessed using profilometry. Contrast sensitivity and visual acuity were measured through the lenses when their powers were neutralized with suitable spectacle trial lenses. RESULTS: Average surface roughness was found to increase with lens power, roughness values being higher for negative lenses than for positive lenses. Losses in visual contrast sensitivity and acuity measured in two subjects were found to follow a similar pattern. Findings are similar to those previously published with other excimer laser systems. CONCLUSIONS: Levels of surface roughness produced by some laser systems may be sufficient to degrade visual performance under some circumstances.     

Tattooing of skin results in transportation and light-induced decomposition of tattoo pigments – a first quantification in vivo using a mouse model

Abstract:  Millions of people are tattooed with inks that contain azo pigments. The pigments contained in tattoo inks are manufactured for other uses with no established history of safe use in humans and are injected into the skin at high densities (2.5 mg/cm²). Tattoo pigments disseminate after tattooing throughout the human body and although some may photodecompose at the injection site by solar or laser light exposure, the extent of transport or photodecomposition under in vivo conditions remains currently unknown. We investigated the transport and photodecomposition of the widely used tattoo Pigment Red 22 (PR 22) following tattooing into SKH-1 mice. The pigment was extracted quantitatively at different times after tattooing. One day after tattooing, the pigment concentration was 186 μg/cm² skin. After 42 days, the amount of PR 22 in the skin has decreased by about 32% of the initial value. Exposure of the tattooed skin, 42 days after tattooing, to laser light reduced the amount of PR 22 by about 51% as compared to skin not exposed to laser light. A part of this reduction is as a result of photodecomposition of PR 22 as shown by the detection of corresponding hazardous aromatic amines. Irradiation with solar radiation simulator for 32 days caused a pigment reduction of about 60% and we again assume pigment decomposition in the skin. This study is the first quantitative estimate of the amount of tattoo pigments transported from the skin into the body or decomposed by solar or laser radiation.     

Medial artery calcification as an indicator of diabetic peripheral vascular disease

BACKGROUND: M?nckeberg sclerosis or medial artery calcification (MAC) is a well-known phenomenon associated with diabetic and other arterial disease. However, its consequence within the foot, and specifically the first dorsal metatarsal artery, has not previously been studied. MATERIALS AND METHODS: Nearly 1,000 foot x-rays were studied over a 9-month period in a busy hospital to identify the prevalence of first dorsal metatarsal artery calcification. The electronic medical notes for all the patients were reviewed to confirm which patients were known to be diabetic. The patients with positive findings were then identified and their HbA1c, creatinine, and previous foot interventions recorded. RESULTS: Of the population studied, 1.4% had medial artery calcification of the 1st dorsal metatarsal artery: 93% were known diabetics and 100% had impaired glucose tolerance (a glucose plasma concentration of greater than 7.8 mmol/l 2-hours post-glucose loading). Seventy-nine percent had required previous podiatric care for foot ulceration and 64% had required surgical intervention for their diabetic feet. MAC has a high positive predictive value (92.9% (95% CI 69.2 to 98.7)) for diabetes, with a good specificity (99.9% (95%CI 99.4 to 100)) and low false positive rate (0.1% (05%CI 0.0 to 0.6)). CONCLUSION: Medial artery calcification in the first dorsal metatarsal artery is characteristic of impaired glucose metabolism, and if seen on routine x-ray should be an indication for screening of the patient. It should also be considered as a foot-at-risk sign in the established diabetic due to the high incidence of foot ulceration and need for surgical intervention in this group.     

Testosterone concentration in young patients with diabetes

OBJECTIVE—We have previously shown that hypogonadotrophic hypogonadism is common in middle-aged patients with type 2, but not with type 1, diabetes. We have now investigated the total and free testosterone concentrations in young (aged 18–35 years) type 1 and type 2 diabetic patients.RESEARCH DESIGN AND METHODS—In this study carried out in a tertiary referral center, serum concentrations of total and free testosterone were measured in 38 type 1 diabetic (mean age 26.45 ± 0.89 years) and 24 type 2 diabetic (mean age 27.87 ± 0.97 years) subjects. The mean BMI of type 1 and type 2 diabetic patients was 27.41 ± 1.18 and 38.55 ± 2.04 kg/m², respectively (P < 0.001).RESULTS—The mean total testosterone concentration of type 1 and type 2 diabetic patients was 22.89 ± 1.23 and 11.14 ± 0.99 nmol/l, respectively (P < 0.001). The mean free testosterone concentration of type 1 and type 2 diabetic patients was 0.489 ± 0.030 and 0.296 ± 0.022 nmol/l, respectively (P < 0.001). Eight of 24 (33%) type 2 diabetic patients had subnormal free testosterone concentrations (<0.225 nmol/l). Using an age-based reference range, 14 of 24 (58%) type 2 diabetic patients had low free testosterone concentrations (<0.278 nmol/l). Three of 38 (8%) type 1 diabetic patients had free testosterone concentrations below the lower limit of normal (P = 0.02 when compared with type 2 diabetes). Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) concentrations in type 2 diabetic patients with low free testosterone concentrations were in the normal range and were similar to those in type 1 diabetic patients.CONCLUSIONS—Young type 2 diabetic patients have significantly lower plasma concentrations of total and free testosterone and inappropriately low LH and FSH concentrations with a very high prevalence of hypogonadotrophic hypogonadism, when compared with type 1 diabetic patients of a comparable age. The potential implications for their sexual and reproductive function during prime reproductive years are profound.We have previously shown that patients with type 2 diabetes have a frequent occurrence of hypogonadotrophic hypogonadism, as reflected in low plasma concentrations of testosterone and inappropriately low luteinizing hormone (LH) and follicle-stimulating hormone (FSH) (1). These studies were carried out in patients with a mean age of 55 years. Other studies (2,3), also carried out in middle-aged populations, have confirmed the frequent occurrence of this defect in type 2 diabetes. We have also shown that the prevalence of this defect is very low in type 1 diabetes (4). In view of the increasing incidence of obesity and type 2 diabetes in younger populations and in children, the occurrence of this defect in younger populations needs to be investigated, since such an abnormality would affect their sexual function, reproductive capacity, and the quality of life during their peak reproductive years. In addition, the lack of testosterone would also potentially promote further weight gain and loss of skeletal muscle and would thus promote insulin resistance (5–7). In view of the above observations, we have now hypothesized that younger patients with type 2 diabetes have significantly lower testosterone concentrations and a higher prevalence of low testosterone concentrations (hypogonadism) when compared with patients with type 1 diabetes.     

Interaction of COMT val158met and externalizing behavior: relation to prefrontal brain activity and behavioral performance

A promising approach in neuroimaging studies aimed at understanding effects of single genetic variants on behavior is the study of gene-trait interactions. Variation in the catechol-O-methyl-transferase gene (COMT) is associated with the regulation of dopamine levels in the prefrontal cortex and with cognitive functioning. Given the involvement of dopaminergic neurotransmission in externalizing behavior, a trait characterized by impulsivity and aggression, especially in men, externalizing (as a trait) may index a set of genetic, environmental, and neural characteristics pertinent to understanding phenotypic effects of genetic variation in the COMT gene. In the current study, we used a gene-trait approach to investigate effects of the COMT val(158)met polymorphism and externalizing on brain activity during moments involving low or high demands on cognitive control. In 104 male participants, interference-related activation depended conjointly on externalizing and val(158)met: stronger activation in the dorsal anterior cingulate and lateral prefrontal cortex was found for val/val individuals with high trait externalizing while stronger activation in cingulate motor areas and sensorimotor precuneus was found for met/met individuals with low externalizing. Our results suggest that the val/val genotype, coupled with high levels of trait externalizing, lowers the efficiency of stimulus conflict resolution, whereas the met/met genotype, coupled with low levels of externalizing, lowers the efficiency of response selection.