Chemical and microbiological parameters in New Orleans floodwater following Hurricane Katrina

Hurricane Katrina, rated as a Category 4 hurricane on the Saffir-Simpson scale, made landfall on the U.S. Gulf Coast near New Orleans, Louisiana on Monday, August 29, 2005. The storm brought heavy winds and rain to the city, and several levees intended to protect New Orleans from the water of Lake Pontchartrain were breached. Consequently, up to 80% of the city was flooded with water reaching depths in excess of three meters in some locations. Research described in this paper was conducted to provide an initial assessment of contaminants present in floodwaters shortly after the storm and to characterize water pumped out of the city into Lake Pontchartrain once dewatering operations began several days after the storm. Data are presented which demonstrate that during the weeks following the storm, floodwater was brackish and well-buffered with very low concentrations of volatile and semivolatile organic pollutants. Dissolved oxygen was depleted in surface floodwater, averaging 1.6 mg/L in the Lakeview district and 4.8 mg/L in the Mid-City district. Dissolved oxygen was absent (< 0.02 mg/L) at the bottom of the floodwater column in the Mid-City district 9 days afterthe storm. Chemical oxygen demand (Mid-City average = 79.9 mg/L) and fecal coliform bacteria (Mid-City average = 1.4 x 10(5) MPN/100 mL) were elevated in surface floodwater but typical of stormwater runoff in the region. Lead, arsenic, and in some cases, chromium, exceeded drinking water standards but with the exception of some elevated Pb concentrations generally were typical of stormwater. Data suggest that what distinguishes Hurricane Katrina floodwater is the large volume and the human exposure to these pollutants that accompanied the flood, rather than very elevated concentrations of toxic pollutants.     

A predictive approach to nutrient criteria

Violation of a water quality standard triggers the need for a total maximum daily load (TMDL); this should result in actions that improve water quality, but sometimes at significant cost. If the standard is well-conceived, a designated-use statement characterizes societal values, and a criterion provides a measurable surrogate for designated use. This latter provision means that scientists measure the criterion and view violations of the criterion as equivalent to noncompliance with the designated use. However, if a criterion is not a good indicator of designated use, it is apt to result in misallocation of the limited resources for water quality improvement through the TMDL process. This concern provides the basis for our assessment of the national nutrient criteria strategy recently proposed by the U.S. EPA. We acquired data sets for four case studies (Lake Washington, Neuse River Estuary, San Francisco Bay, and Lake Mendota) and then used expert elicitation to quantify designated-use attainment for each case. Applying structural equation modeling, we identified good water quality criteria as the best predictors of the designated use elicited response variable. Further, we used the model to relate the level (concentration) of each criterion to the probability of compliance with the designated use; this provides decision-makers with an estimate of risk associated with the criterion level, facilitating the selection of appropriate water quality criteria.     

The potential for acquiring cryptosporidiosis or giardiosis from consumption of mung bean sprouts in Norway: a preliminary step-wise risk assessment

The current work evolved from a microbial survey of fruits and vegetables conducted in Norway between 1999 and 2001. This survey found that mung bean sprouts were more likely to be contaminated with Cryptosporidium and Giardia than the other produce included in the survey. To support this observation and to demonstrate to public health officials that this might be a risk warranting further attention, a simple risk assessment was initiated. Assuming that 60,000 people in Norway consume a single serving of bean sprouts per week, and contamination levels are similar to those found in the survey, it was calculated that there could be in the order of 20 cases of Giardia or Cryptosporidium infection per 100,000 population attributable to consumption of mung bean sprouts. A number of assumptions were made for the calculations, including parasite factors (e.g. viability, genotype), product factors (e.g. extent of product contamination) and host factors (e.g. composition and extent of consumer group). These assumptions and areas of uncertainty, where further data would improve the risk assessment, are highlighted throughout. Not only does the risk assessment identify new areas of research, but it also demonstrates how risk assessment can be used as a tool to try to influence public health surveillance.     

Movement and persistence of Salmonella in broiler chickens following oral or intracloacal inoculation

The dissemination of Salmonella into various lymphoid-like organs in young broiler chicks after oral and intracloacal inoculation was studied. A three-strain cocktail of Salmonella Typhimurium, Salmonella Montevideo, and Salmonella Enteritidis was administered either orally or intracloacally to day-old chicks. After 1 h, 1 day, or 1 week, the ceca, thymus, liver and gallbladder, spleen, and bursa were sampled for the presence of Salmonella. There was a marked difference in the recovery of Salmonella 1 h postinoculation. Only 6 of 50 samples from orally inoculated chicks were positive compared with 33 of 50 samples from cloacally inoculated samples. In comparison, 24 h and 1 week after inoculation, there was no difference in the number of positive samples between oral or cloacal inoculation. The rapidity of the translocation of the Salmonella from the cloacal inoculum compared to the oral inoculum is likely due to the transient time required for Salmonella to move through the alimentary tract. The method of inoculation did not affect the distribution of serogroups. Of the three serotypes in the composite inoculum, the Salmonella Enteritidis (group D) was recovered only twice in replication 1 and not at all in replication 2. Both the Salmonella Typhimurium (serogroup B) and the Salmonella Montevideo (serogroup C1) were recovered extensively throughout the study.     

Differentiation of Competitive vs. Non-competitive Mechanisms Mediating Disruption of Moth Sexual Communication by Point Sources of Sex Pheromone (Part I): Theory1

This study establishes a theoretical framework for differentiating among possible behavioral mechanisms whereby sexual communication of moths is disrupted in crops treated with point sources of pheromone. The major mechanisms recognized in the mating disruption literature fall into two main categories: competitive (competitive attraction = false-plume-following) and non-competitive (camouflage, desensitization, and sensory imbalance). Each disruption mechanism has been precisely defined verbally, and then the distinguishing characteristics of the two categories were defined mathematically. The sets of predictions associated with each category were visualized by graphical plots of mathematical simulations. Profiles of simulated male visitation rates to pheromone-baited traps deployed in pheromone-treated crops were graphed against density of pheromone dispensers by using various types of axes. Key traits of non-competitive attraction are as follows: concave profiles on untransformed axes, with an asymptotic approach to zero catch of male moths in traps; a straight line with positive slope when 1/catch is plotted against dispenser density (Miller-Gut plot); and a straight line with negative slope when catch is plotted against dispenser density * catch (Miller-de Lame plot). Key traits of non-competitive disruption profiles include: an initial linear disruption profile on untransformed axes; a concave Miller-Gut plot; and a recurving Miller-de Lame plot. These differences in profiles provide a basis for distinguishing competitive from non-competitive mechanisms when analyzing disruption profiles from field experiments. Slopes and intercepts of these secondary plots can also reveal both male and female moth densities, if the relative attractiveness of traps, females, and dispensers is known. The absolute value of the slope of the Miller-de Lame plot is a measure of each dispenser’s activity (D _a) for suppressing catch of male moths in traps. An application activity (D _Āa) for a given dispenser can be calculated by multiplying D _a by the number of such dispensers applied per hectare of crop. ¹As this study progressed, striking similarities were noted between the kinetics of mating disruption by competitive attraction and enzyme kinetics. Because of space limitations, this congruence will be addressed in a future report.     

Surface plasmon based thermo-optic and temperature sensor for microfluidic thermometry

We report on a noninteracting technique for the thermal characterization of fluids based on surface plasmon resonance interrogation. Using liquid volumes less than 20 μl, we have determined the materials' thermo-optic coefficients with an accuracy of better than 1×10(-5) °C(-1) and demonstrated temperature sensing with an accuracy of 0.03 °C. The apparatus employs a low-power probe laser, requiring only a single wavelength, polarization, and interrogation angle for accurate characterization. The device is particularly suited for precise diagnostics of liquids and gases within microfluidic systems and may also be readily integrated into a variety of lab-on-chip platforms, providing rapid and accurate temperature diagnostics.     

Effects of feeding propionibacteria to dairy cows on milk yield, milk components, and reproduction

Two weeks before parturition, 38 Holstein primiparous and multiparous cows were assigned to 1 of 3 treatment groups: control animals (n = 13) received regular total mixed rations (TMR), the low-dose group (n = 14) received the control TMR plus 6 x 10(10) cfu/cow of Propionibacterium strain P169 (P169), and the high-dose group (n = 11) received the control TMR plus 6 x 10(11) cfu/cow of P169 from -2 to 30 wk postpartum. Weekly milk samples were analyzed for percentage of milk fat, protein, lactose, and SNF, milk urea nitrogen, and somatic cell counts. Daily milk production expressed as 4% fat-corrected milk was affected by treatment and week x parity. High-dose and low-dose P169-treated cows exhibited 7.1 and 8.5% increases above controls in daily 4% fat-corrected milk, respectively. Treatment x parity and week significantly influenced percentage of milk fat, lactose, and protein, whereas treatment x parity and treatment x week influenced SNF. Ruminal propionate levels were influenced by treatment such that high-dose P169 cows had greater molar percentage of propionate than did low-dose P169 and control cows. Change in body weight postpartum was influenced by week x parity and treatment x parity such that high-dose and low-dose P169 multiparous cows exhibited a more rapid recovery of wk-1 body weight than did control multiparous cows. There was no treatment, parity, or interaction on days to first postpartum ovulation or on estrous behavior at 45 and 90 d postpartum. We concluded that P169 might have potential as an effective direct-fed microorganism to increase milk production in dairy cows.     

Deviations in populations of peripheral blood mononuclear cells and endometrial macrophages in the cow during pregnancy

The presence of conceptus alloantigens necessitates changes in maternal immune function. Here, we used the cow to evaluate whether species with epitheliochorial placentation have changes in specific leukocyte populations during pregnancy similar to those reported in species with hemotropic placentae. At days 33-34 of pregnancy, there was no effect of pregnancy status on the number of cells positive for CD8, CD4, gammadeltaT cell receptor, or the monocyte marker CD68 in the peripheral blood mononuclear cell (PBMC) population. There was, however, an increase in the proportion of CD4(+) cells that were positive for CD25. There was no effect of status on the proportion of PBMCs that were CD8(+) when comparing preparturient cows to nonpregnant cows. However, preparturient cows had an increased percentage of PBMCs that were gammadeltaT cells and CD4(+)CD25(+) and a tendency for a lower percentage that were CD68(+) cells. Using immunolocalization with anti-CD68, it was found that pregnant cows had increased numbers of CD68(+) cells in the endometrial stroma as early as days 54-100 of gestation; this increase persisted through the last time examined (day 240 of gestation). Cells positive for CD68 were also positive for another macrophage/monocyte marker, CD14. In conclusion, pregnancy in the cow is associated with changes in peripheral and endometrial leukocyte numbers, which are similar to patterns observed in other species.     

Effect of heat on the distribution of fluorescently labeled plasminogen and plasminogen activators in bovine skim milk

ABSTRACT:  Differentially fluorescently labeled bovine plasminogen (PG-594) and human tissue- and urokinase-type plasminogen activators (tPA-647 and uPA-546) were added to bovine skim milk to track the effect of heat on the location and concentration of these plasmin system components following acid precipitation or ultracentrifugation. In unheated milk, the majority (71.7% to 89.0%) of the added PG and PAs associated with casein micelles or acid curd, and PG-594 in the serum fraction was partially due to associations with nonsedimentable caseins. Heat treatment (85 °C for 16 s) significantly ( P < 0.05) affected distribution of PG-594, tPA-647, and uPA-546, resulting in reduced concentrations of PG and PAs in the serum fractions and reciprocal increases in their levels in the nonsedimentable casein fractions. Overall, almost all of the added PG and PAs (95.9% to 97.5%) became associated with caseins following heat treatment. This is the 1st study to successfully use fluorescent labeling to quantify effects of heat on the location of plasmin components in skim milk.     

Lattice-resolution contrast from a focused coherent electron probe. Part I

To develop a Bloch wave framework for lattice-resolution contrast derived from coherent or incoherent scattering of an electron probe focused onto a crystal, boundary conditions which influence the propagation of an arbitrarily distorted coherent electron probe are addressed. These boundary conditions are particularly relevant for a probe focused within a unit cell, and lead to a general theory which hinges on Bloch wave excitation amplitudes being written as a function of beam position and focus. Whereas antisymmetric Bloch states are not excited for an incident plane wave at an exact zone axis orientation, these states may be strongly excited depending on probe focus and position within the unit cell. Equations for both coherent and incoherent lattice image contrast in scanning transmission electron microscopy are derived for any detector configuration in the Bloch wave framework. An equivalent expression amenable to evaluation via multislice techniques is also described. It is shown explicitly how mixed dynamic form factors for incoherent scattering should be taken into account for annular dark field or backscattered electron detectors, as well as for characteristic losses detected by X-ray emissions or by electron energy loss spectroscopy. A background contribution from "absorbed" electrons is included in the theory. The contribution of cross-talk from neighbouring columns to incoherent contrast is examined within the context of this theoretical framework.