A histopathologic study of macular cysts and holes

Forty-four eyes from 39 patients with either lamellar macular holes (17 eyes), full-thickness macular holes (18 eyes), and/or macular cysts (9 eyes) were studied histopathologically. Lamellar and full-thickness holes were frequently found in eyes with a history of trauma or ocular surgery. Diabetes mellitus was the most common condition associated with macular cysts. Four lamellar holes and four full-thickness holes occurred in eyes with senile macular degeneration. Six lamellar holes, eight full-thickness holes, and one macular cyst developed on an idiopathic basis. Residual cystoid macular edema was the most prevalent accompanying pathologic feature. Cystoid macular edema was also noted in the opposite eye in seven cases of lamellar and full-thickness holes. A preretinal glial membrane, thought to be a secondary change, was found at or near the edges of the lamellar or full-thickness holes or over the macular cyst in the majority of cases. Wrinkling of the internal limiting membrane (ILM) was present in five cases. Vitreous traction, with or without an operculum, was infrequently associated with these entities.     

Cysteine and cystine transport at the blood-brain barrier

The nature of cysteine and cystine uptake from the cerebral capillary lumen was studied in the rat using the carotid injection technique, [35S]-Cysteine uptake was readily inhibited by the synthetic amino acid 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH), the defining substrate for the leucine-preferring (L) system in the Ehrlich ascites cell. The addition of nonradioactive alanine or serine, representatives of the alanine, serine, and cysteine-preferring (ASC) system, produced no significant decrease in the uptake of cysteine after cysteine transport by the L system was blocked with BCH. This indicated that the major component of cysteine's transport from the brain capillary lumen was by the L system with no detectable uptake of cysteine by the ASC system. No carrier-mediated transport of cystine, the disulfide form of the amino acid, was detected, nor was there any inhibition by cystine of the transport of the neutral amino acid methionine or the basic amino acid arginine. These results suggest that the ASC system, if present, is not quantitatively important for the transport of neutral amino acids from the brain capillary lumen.     

The effect of wastewater phosphorus removal on shagawa lake, Minnesota: phosphorus supplies, lake phosphorus and chlorophyll a

In early 1973, the phosphorus supply to Shagawa Lake, Minnesota, was reduced by about 80% when a tertiary wastewater treatment plant began operating. Significant reductions in total and soluble reactive phosphorus concentrations have occurred in the lake since that time. By 1976 the average (volume weighted over the entire lake) total and soluble reactive phosphorus concentrations had declined from about 51 and 21 μg l⁻¹ to about 30 and 4.5 μg l⁻¹, respectively, corresponding to 40 and 80% reductions. During 1975 and 1976, chlorophyll a (averaged over the top 5 m) had decreased to less than 50% of the pretreatment level during May-June but during July-August little change had occurred.

A phosphorus residence time model projected equilibrium total phosphorus concentrations of about 12 μg l⁻¹ within 1.5 years. The fact that this level was not reached is attributed to a feedback of phosphorus from the sediments, primarily during summer. This phenomenon has been incorporated into a modified total phosphorus mass balance model which projects the phosphorus pattern through 1976 quite accurately. The close fit of the modified mass balance model implies that the phosphorus supply from the sediments has not diminished since treatment since treatment began, and that further recovery of the lake will depend upon how long this feedback of phosphorus from the sediments continues.     

The decomposition voltage of aluminium reduction cells. The influence of the alumina content in the bath

The decomposition voltage on 75 kA aluminium reduction cells with Søderberg anodes was measured by extrapolation of current-voltage curves and by use of an aluminium reference electrode. Both methods yielded results in the range 1.50 V–1.85 V, although higher and lower values occasionally occurred. The anode-reference voltage as well as the cell voltage showed a marked increase when the alumina content in the bath decreased below 2 wt%, and the anode effect was approached. This behaviour is in good agreement with theoretical curves based on laboratory data on anodic over-voltage and electrical conductivity.     

Impact of commercial preharvest transportation and holding on the prevalence of Salmonella enterica in cull sows

The objective of this study was to examine the prevalence of Salmonella enterica in cull sows at various stages from the farm to the abattoir. Cull sows (n=181) were sampled over 10 weeks. Fecal samples (10 g each) were collected on the farm ca. 24 h before loading and at the live-hog market ca. 3 h before loading. Samples (ileocecal lymph nodes, cecal contents, feces from the transverse colon, ventral thoracic lymph nodes, subiliac lymph nodes, sponge swabs of the left and right carcass sections, and chopped meat) were collected at the abattoir. The percentages of positive fecal samples on the farm and at the live-hog market were 3% (5 of 181 samples) and 2% (3 of 181 samples), respectively. After transport from the live-hog market (10 h) and holding at the abattoir (6 h), 41% (74 of 180) of cull sows yielded S. enterica in one or more sampled tissues. The isolation rate for total cecal contents (33%; 60 of 180 samples) was significantly (P<0.05) higher than those for ileocecal lymph nodes (7%; 12 of 181 samples), feces (11%; 20 of 181 samples), and ventral thoracic and subiliac lymph nodes (2%; 4 of 181 samples). Before a 2% lactic acid carcass wash (lasting 8 to 9 s), 14% (25 of 180) of carcasses were positive, compared with 7% (12 of 179) after the wash (P<0.05). Two S. enterica serotypes, Derby and Infantis, were found on the farm and at the live-hog market. At the abattoir, 12 serotypes that had not previously been found on the farm or at the live-hog market were recovered. The results of this study demonstrate that transport and holding practices may contribute to an increase in S. enterica infection prior to slaughter to levels much higher than those found on the farm.     

Analysing transformation products of herbicide residues in environmental samples

High-performance liquid chromatography (HPLC) methods were developed for the optimised determination of five herbicide residues (dichlorprop, isoproturon, mecoprop, metsulfuron-methyl and 2,4,5-T) and major metabolites. These compounds represent important groups of herbicides and several residues have been found as contaminants in groundwater. The methods make it possible to study these herbicides and several transformation products through simultaneous detection and quantification. Culture media as well as cleaned up extracts from sediment and groundwater can be analysed. Using HPLC with UV detection the general limit of quantification was 1.8 ng injected corresponding to a detection limit of 1-2 micrograms/l when analysing a cleaned up extract from a 20 ml water sample. The method was verified by analysing herbicide residues in groundwater collected from a wetland area. Cleaning up 20 ml groundwater with a residue level of 25 micrograms/l the general recovery was within 58-82%.