Radiation retinopathy: electron microscopy of retina and optic nerve.

A 4 1/2 year old female was treated for embryonal rhabdomyosarcoma of the left orbit in 1975 with radiation (59.5 Gy in 5 weeks), followed by chemotherapy. An electroretinogram (ERG) in March, 1988 revealed cone responses 3% of normal and no rod responses in the left eye, and normal responses in the right eye. The eye was enucleated in April 1988. In the fovea no choroidocapillaris was seen at the intact Bruch's membrane, and the pigment epithelium was preserved only in small patches. No photoreceptor cells were seen in the areas devoid of pigment epithelial cells. The parafoveal and peripheral (30 degrees eccentricity) retina was better preserved. The thickness of the layer of rods and cones and of Henle's fiber layer was reduced. Very few outer segments were present. Macrophages had invaded the retinal tissue in moderate numbers. The retinal vessels were ensheathed by several layers of collagen fibrils. The spatial densities of pigment epithelial, cone, rod, and bipolar cells had been reduced. The optic nerve contained a total number of 1,022,000 nerve fibers.     

Mass Flow Balances of Triclosan in Small Rural Wastewater Treatment Plants and the Impact of Biomass Parameters on the Removal

Three United Kingdom (UK) wastewater treatment plants (WWTP) – rotating biological contactor (RBC), trickling filter (TF) and oxidation ditch (OD) – were analyzed for their triclosan contents at different treatment stages. Furthermore, selected wastewater and biomass parameters were determined to draw correlations between the biological treatment, biomass make‐up and the removal efficiency of triclosan. Within this study, triclosan bound to the extracellular polymeric substances (EPS) of sludge flocs in the oxidation ditch seemed to have an adverse effect on the effluent quality, reducing the triclosan overall removal due to re‐balancing effects within the final clarifier. Within this study of the three examined WWTPs, temperature and pH of the bulk phase and as well the lipid content of the biomass seemed to have the most significant effects on the triclosan removal. The triclosan overall removal for each site was shown to be significantly high, ranging on average between 81 % (RBC) and 96 % (OD). The most efficient plant regarding the triclosan overall removal was found to be the oxidation ditch, which can be explained due to high hydraulic retention times. Primary settling points were found to have a significant impact on the triclosan overall loss rate, which was associated with the high fat content of primary sludge and the hydrophobic properties of triclosan. Besides the fat content of sludge or biomass, the pH and temperature showed a significant impact on triclosan loss rates as well.     

Continuous, intermitted and sporadic motor unit activity in the trapezius muscle during prolonged computer work.

The Cinderella hypothesis postulates the continuous activity of specific motor units (MUs) during low-level muscle contraction. The MUs may become metabolically overloaded, with the subject developing muscle pain and strain. The hypothesis requires MUs that are active for a time long enough to actually damage muscle fibers. The aim of this study was to determine if there are continuously active MUs in the right trapezius muscle during normal computer work using a computer mouse. Fourteen healthy subjects executed an interactive computer-learning program (ErgoLight) for 30 min. Six-channel intramuscular EMG and two-channel surface EMG signals were recorded from two positions of the trapezius muscle. Decomposition was achieved with automated, multi-channel, long-term decomposition software (EMG-LODEC). In two out of the 14 subjects, three MUs were continuously active throughout the 30 min. Although the majority of the MUs were active during only part of the experimental session, an ordered on-off behavior (e.g. substitution) pattern was not observed. As long-lasting activity was verified in some subjects, the results support the Cinderella hypothesis. However, it cannot be concluded here how long the MUs could stay active. If continuous activity overloads low threshold MUs, the potential exists for selective fibre injuries in low threshold MUs of the trapezius muscle in subjects exposed to long-term computer work.