Cultured epidermal keratinocytes provide an abundant supply of biologic material for wound treatment. Because restoration of barrier function is a definitive criterion for efficacy of wound closure and depends on the lipids present in the epidermis, we analyzed lipid composition of the epidermis in cultured skin substitutes in vitro and after grafting to athymic mice. The cultured skin substitutes were prepared from human keratinocytes and fibroblasts attached to collagen-glycosaminoglycan substrates. After 14 days of incubation, cultured skin substitutes were grafted orthotopically onto full-thickness wounds in athymic mice. Samples for lipid analysis were collected after 14 and 34 days of in vitro incubation, and 3 weeks and 4 months after grafting. Both in vitro samples show disproportions in epidermal lipid profile as compared with the native human epidermis, i.e., a low amount of phospholipids (indicating imbalance in proliferation and differentiation); a large excess of triglycerides (storage lipids); and low levels of free fatty acids, gluco-sphingolipids, cholesterol sulfate, and ceramides-suggesting abnormal composition of stratum corneum barrier lipids. Fatty acid analysis of cultured skin substitutes in vitro revealed insufficient uptake of linoleic acid, which resulted in increased synthesis of and substitution with monounsaturated fatty acids, mainly oleic acid. These abnormalities were partially corrected by 3 weeks after grafting; and 4 months after grafting, all epidermal lipids, with some minor exceptions, were synthesized in proportions very similar to human epidermis. Results of this study show that grafting of cultured skin substitutes to a physiologic host permits the recovery of lipid in proportion to that required for barrier formation in normal human epidermis.

Effect of irrigation with groundwater (GW), primary‐treated wastewater (PTWW), secondary‐treated wastewater (STWW), and roof‐collected rainwater (RCR) on the microbial quality of lettuce cultivars “Annapolis,” “Celinet,” and “Coastline” grown in high tunnel was investigated. Lettuce plants were spray irrigated with irrigation waters once a week for 2 weeks and analyzed for indicator and pathogenic bacteria. PTWW irrigation resulted in the highest Escherichia coli recovery on the lettuce plants (4.7 log MPN/g) as compared to irrigation with other three waters on 0 day postirrigation (dpi). Lettuce cultivars affected the bacterial die‐off rate, where E. coli populations reduced the most by 1.5 log MPN/g on “Annapolis” lettuce on 2 dpi. The STWW and RCR irrigation did not significantly influence indicator bacterial populations on lettuce as compared to GW irrigation. The STWW and RCR containing low populations of indicator bacteria may be suitable for lettuce irrigation in Mid‐Atlantic area without affecting its microbial quality.

Assessing microbial quality of irrigation water is important to prevent foodborne illnesses caused by fresh produce contamination. Generic Escherichia coli and enterococci are commonly used to evaluate the microbial water quality. The objective of this study was to see if patterns in spatial distributions of the fecal indicator bacteria concentrations along a creek at baseflow that are preserved over time can be detected. Such patterns are commonly referred to as temporally stable patterns. Microbial concentrations were measured along the Conococheague Creek in Pennsylvania during 3 yr on weeks when the creek was at base flow. The upstream sampling location was at the outlet of the forested subwatershed, next two locations were in agricultural area dominated by crops and pastures, and another two were in urbanized areas. Empirical orthogonal functions (EOFs) have been applied to detect a temporally stable spatial pattern. The most significant spatial pattern of both bacteria was followed the change of land use; 74.6 and 68.6% were explained by the first EOF for E. coli and enterococci, respectively. Much less variability (19.6 and 17%) was explained by impacts of tributary and braided sections of the creek. A good approximation of the average logarithms of concentrations across the studied reach was provided by logarithms of concentrations at the sampling location where the first EOF was close to zero. We confirmed that EOF analysis can uncover the significant multiple temporally stable spatial patterns for the fecal indicator bacteria concentration along the creek in the presence of multiple land uses.

<p>Fecal indicator bacteria (FIB), <em>Escherichia coli,</em> and enterococci are used to define regulatory thresholds for microbial water quality of streams and bodies of water and water body waters used for recreation and irrigation. Bottom sediments serve as secondary habitats for FIB that can enter water columns and alter microbial water quality, notwithstanding waste management at surrounding lands. Therefore, monitoring of indicator bacteria in bottom sediments is important. The discovery of persistent spatial patterns of environmental variables has been beneficial in environmental monitoring. Such patterns often termed temporal stability manifestation, helped substantially decrease the number of monitoring locations by estimating the spatial variation across the observation area according to the established spatial patterns. Temporal stability of indicator bacteria concentrations was observed in water columns of streams and ponds but was so far never researched for bottom sediments.</p> <p>This work aimed to investigate the temporal stability of E. coli and enterococci concentrations along a reach of the Conococheague creek in the  USGS Conococheague-Opequon Subbasin). Three monitoring sites - TP, I81, and SS  were established where the creek collected the surface runoff from the forested headwater, agricultural, and mixed urban and agricultural areas, respectively. Sediment samples were taken collected weekly continuously for three years. FIB concentrations were measured by membrane filter method for E. coli using the mTec agar and enterococci using the mEI agar. The temporal stability was quantified using the mean relative differences (MRD) of concentrations. To obtain the relative differences for each location, the ratios of logarithms of concentration at each location and the average logarithm of concentrations across all locations were decreased by one for each observation time. MRDs were the relative differences for each location averaged over all observation times.</p> <p>The sediment was sandy. Annual amplitudes of concentrations of both FIB in sediments were about three orders of magnitude in the range from 1 to 7000 colony forming units (g dry weight)-1. The sine function with the maximum in July and minimum in February gave a reasonable approximation of the annual dynamics at all locations over three years. The MRD values were equal to -0.198± 0.023, -0.012±0.019, and 0.210±0.021 for E. coli and -0.160±0.023, 0.000±0.017, and 0.165±0.024 for enterococci (mean standard error) at TP, I81, and SS locations, respectively. When converted to absolute values, concentrations were on average about 60% higher at SS than at I81, and 60% lower at TP than at I81. Values of MRD over warm (April-September) and cold (October-March) seasons followed the same pattern as the above annual values, with the range of MRD slightly larger over the cold season and somewhat smaller over the warm season as compared with the annual values.</p> <p>Qualitative metrics also indicated the prevalence of specific spatial patterns. In particular, <em>E. coli</em> (enterococci) concentrations at TP, I81, and SS were smaller than at two other sites in 65% (63%),  28%(24%), and 6%(13%)  of observation times, respectively. </p> <p>Overall, three years of observations showed that persistent spatial patterns were present and manifested themselves against the backdrop of persistent temporal oscillatory annual patterns.</p>