Quantitative spectroscopy of single molecule interaction times.

Single molecule fluorescence tracking provides information at nanometer-scale and millisecond-temporal resolution about the dynamics and interaction of individual molecules in a biological environment. While the dynamic behavior of isolated molecules can be characterized well, the quantitative insight is more limited when interactions between two indistinguishable molecules occur. We address this aspect by developing a theoretical foundation for a spectroscopy of interaction times, i.e., the inference of interaction from imaging data. A non-trivial crossover between a power law to an exponential behavior of the distribution of the interaction times is highlighted, together with the dependence of the exponential term upon the microscopic reaction affinity. Our approach is validated with simulated and experimental datasets.

Biodegradation of chlorobenzene in a constructed wetland treating contaminated groundwater.

Monochlorobenzene (MCB) is an important groundwater contaminant world-wide. In this study, a horizontal subsurface flow constructed wetland with an integrated water compartment was fed with MCB contaminated groundwater originating from the local aquifer. Analysis of spatial concentration dynamics of MCB and oxygen was combined with isotope composition analysis of MCB for assessing in situ biodegradation. Removal of MCB was most effective in the upper layer of the soil filter, reaching up to 77.1%. Trace oxygen concentrations below 0.16 mg L(-1) were observed throughout the wetland transect, suggesting a considerable limitation of aerobic microbial MCB degradation. Enrichment of 13C in the residual MCB fraction at increasing distance from the inflow point indicated microbial MCB degradation in the wetland. The observed isotope shift was higher than expected for aerobic MCB degradation and thus pointed out a significant contribution of an anaerobic degradation pathway to the overall biodegradation.

Reversible changes of visual acuity and pattern-electroretinograms after blue-green argon laser photocoagulation of diabetic patients.

Visual acuity, color vision, pattern-visual-evoked-potentials (P-VEPs) and pattern-electroretinograms (P-ERGs) were measured in 13 diabetic subjects before, and 24 hours and 5 weeks after blue-green argon laser treatment. As control, the same examinations were performed in 7 normal subjects and 7 diabetic patients before and after slit lamp examination with the Goldman three mirror contact lens. Visual acuity and P-ERG amplitudes were significantly reduced one day after the laser treatment, while 5 weeks after the laser coagulation, visual acuity and P-ERG amplitudes recovered to pretreatment values. The control group showed no significant changes after slit lamp examination. Since fluorescein angiography revealed no macular changes after laser treatment, the possibility of a reversible functional light damage after blue-green argon laser coagulation (ALC) is discussed.

[Significance of arterial blood pressure for the development of microalbuminuria and retinopathy in type I diabetes mellitus]. / Bedeutung des arteriellen Blutdruckes für das Auftreten einer Mikroalbuminurie und Retinopathie bei Typ I Diabetes mellitus.

The role of hypertension for the combined occurrence of incipient diabetic nephropathy and diabetic retinopathy (RP) was evaluated in 155 insulin-dependent diabetic patients (74 male/81 female); mean age 32.4 +/- 12.2 STD years; means diabetes duration 12.8 +/- 10 STD years). Albumin excretion rate (AER) was measured in 24 hours urine samples by RIA, retinal status was determined by both, fundoscopy and fluorescein angiography. Analysis of the data revealed a statistically significant correlation between the duration of disease and elevated AER (p less than 0.012), and the occurrence of retinopathy (p less than 0.0001). Although there was a close correlation between retinopathy and elevated AER (p less than 0.0001), it is remarkable that 31% of the patients with normal AER (less than 15 micrograms/min) showed signs of non proliferative RP. On the other hand 30% of patients without retinal changes showed an elevated AER (less than 15 micrograms/min). In the group of microalbuminuric patients (greater than 15 micrograms/min) systolic (p less than 0.004) and diastolic (p less than 0.04) blood pressures were significantly higher than in normoalbuminuric patients (less than 15 micrograms/min). Patients with proliferative retinopathy showed significantly higher systolic and diastolic (p less than 0.015) blood pressures compared to patients without retinal changes, though albumin excretion rates were not different in both groups of patients. In conclusion, our results show that diabetic nephropathy and diabetic retinopathy do not develop simultaneously in a representative number of insulin-dependent diabetic patients, but hypertension may be a major risk factor for the development of both microangiopathic complications.

[Long-term ophthalmologic follow-up of diabetic children]. / Ophthalmologische Langzeitbeobachtungen kindlicher Diabetiker.

Sixty-four infant diabetics were kept under observation for an average of 6.1 years to obtain ophthalmologic and endocrinologic data (biomicroscopic fundus examination, fundus photography, fluorescein angiography; blood sugar level, HbA1c determination, ketoacidosis, microalbuminuria, HLA-DR typing). In 28 patients (44%, Group B) retinal vascular changes corresponding to the picture of diabetic preretinopathy were detected by fluorescein angiography. In 36 children (56%, Group A), the retinal vascular system was normal. In 16 patients vascular anomalies increased during the observation period, while in 12 patients no further changes were seen. On comparing the endocrinologic findings in the two groups, the only statistically significant difference was in the ketoacidosis values. A tendency to hypoglycemic attacks, as well as elevated HbA1c and microalbuminuria levels, was likewise more frequent in Group B. Aside from the typical distribution, HLA-DR typing revealed a considerable percentage of children with 1/4 localization in Group B only. It was not seen in any patient in Group A. These results give rise to the hope that HLA-DR typing will enable prognostic conclusions to be drawn concerning the time of onset and progression of diabetic retinal alterations in the future.

[Long-term study following panretinal argon laser coagulation in proliferative diabetic retinopathy]. / Langzeitbeobachtung nach panretinaler Argonlaserkoagulation bei proliferativer diabetischer Retinopathie.

Fifty-eight Type I diabetics were followed up for a minimum of 5 years after panretinal argon laser coagulation in both eyes for proliferative diabetic retinopathy. During the course of this study, 18 patients were excluded because thorough follow-up examinations according to our systematic approach had become impossible. The results of this study indicate that successful photocoagulation depends essentially on the initial findings, on the type and extent of treatment as well as on regular and thorough follow-up examinations.

[Changes in the visual field and dark adaptation following panretinal photocoagulation in diabetic retinopathy]. / Veränderungen des Gesichtsfeldes und der Dunkeladaptation nach panretinaler Photokoagulation bei diabetischer Retinopathie.

Within the past 5 years panretinal photocoagulation was performed in both eyes of 36 patients (Type I diabetics) with proliferative retinopathy. The age of these patients was between 21 and 38 years. The average follow-up period was 3.6 years. The effects on visual acuity, visual field, and dark adaptation were examined: in 65.3% of the cases (47 eyes) visual acuity remained unchanged; in 34.7% (25 eyes) central visual acuity was reduced. Depending on the coagulation technique and the number of coagulates applied, the visual field narrowed in a more or less pronounced way. Moreover, in all patients the dark adaptation threshold was elevated after panretinal photocoagulation.

[Retinal pseudothrombosis]. / Pseudothrombosis retinae.

As opposed to florid diabetic retinopathy, pseudothrombosis in type I diabetics has a favorable prognosis and responds well to panretinal photocoagulation therapy. In the past decade eight cases of retinal pseudothrombosis were evaluated, treated and kept under observation at the department for diabetic eye complications of the 1st University Eye Clinic, Vienna. Photocoagulation therapy repeated at brief intervals halted progression in all cases and improved visual acuity. In the follow-up period (2-10 years) no further episodes of progression were seen.

[Diabetic choroidopathy--a retrospective fluorescein angiography study. Preliminary report]. / Diabetische Chorioidopathie--eine retrospektive fluoreszenzangiographische Studie. Vorläufige Mitteilung.

Both histologic studies and findings with Indocyanin green angiography furnish clear indications of the existence of diabetic choroidopathy. Out of 19,387 fluorescein angiograms made over the last 15 years at the First Ophthalmological Clinic of Vienna University, 902 were selected in which the choroidal vascular system is at least partially visible due to melanin hypopigmentation. The pathologic changes in the choroid observed in these angiograms can be allocated in two basic types of pathologic fluorescence: on the one hand hyperfluorescent lesions such as drusen in Bruch's membrane in suprisingly young diabetics, extremely hyperfluorescent lobules of the choriocapillaris, choroidal aneurysms, and neovascularizations; on the other hand, hypofluorescent lesions or structures were observed, such as delayed filling of the choriocapillaris and, in the late phase of angiography, varicose and tortuous choroidal vessels, drained and appearing dark in contrast to the diffuse background fluorescence.