Optimal sampling locations to reduce uncertainty in contamination extent in water distribution systems

Drinking water utilities rely on samples collected from the distribution system to provide assurance of water quality. If a water contamination incident is suspected, samples can be used to determine the source and extent of contamination. By determining the extent of contamination, the percentage of the population exposed to contamination, or areas of the system unaffected can be identified. Using water distribution system models for this purpose poses a challenge because significant uncertainty exists in the contamination scenarios (e.g., injection location, amount, duration, customer demands, contaminant characteristics). This article outlines an optimization framework to identify strategic sampling locations in water distribution systems. The framework seeks to identify the best sampling locations to quickly determine the extent of the contamination while considering uncertainty with respect to the contamination scenarios. The optimization formulations presented here solve for multiple optimal sampling locations simultaneously and efficiently, even for large systems with a large uncertainty space. These features are demonstrated in two case studies.

Paternal line multigenerational passage of altered risk assessment behavior in female but not male rat offspring of mothers fed a low protein diet

Maternal low protein (MLP) diets in pregnancy and lactation impair offspring brain development and modify offspring behavior. We hypothesized multigenerational passage of altered behavioral outcomes as has been demonstrated following other developmental programming challenges. We investigated potential multigenerational effects of MLP in rat pregnancy and/or lactation on offspring risk assessment behavior. Founder generation mothers (F0) ate 20% casein (C) or restricted (R) 10% casein diet, providing four groups: CC, RR, CR, and RC (first letter pregnancy, second letter lactation diet) to evaluate offspring (F1) effects influenced by MLP in F0. On postnatal day (PND 250), F1 males were mated to non-colony siblings producing F2. On PND 90, F2 females (in diestrous) and F2 males were tested in the elevated plus maze (EPM) and open field. Corticosterone was measured at PND 110. Female but not male CR and RC F2 made more entries and spent more time in EPM open arms than CC females. Overall activity was unchanged as observed in male F1 fathers. There were no open field differences in F2 of either sex, indicating that multigenerational MLP effects are due to altered risk assessment, not locomotion. MLP in pregnancy reduced F1 male and F2 female corticosterone. We conclude that MLP in pregnancy and/or lactation increases the innate tendency to explore novel environments in F2 females via the paternal linage, suggesting lower levels of caution and/or higher impulsiveness to explore unknown spaces. Further studies will be necessary to identify the epigenetic modifications in the germ line through the paternal linage.

Incidence of acute kidney injury following cardiac catheterization prior to cardiopulmonary bypass in children

OBJECTIVES

To determine whether contrast administration was a risk factor for development of acute kidney injury (AKI) in cyanotic congenital heart disease (CHD) patients undergoing cardiopulmonary bypass (CPB).

BACKGROUND

AKI following CPB or contrast administration is well described. In previous studies, administration of contrast prior to CPB has been shown to increase the risk of AKI. Chronic cyanosis leads to glomerular damage and dysfunction, thus potentially placing this population at increased risk of developing AKI following contrast administration prior to CPB.

METHODS

One hundred twenty-two patients with cyanotic CHD undergoing preoperative cardiac catheterization (PCC) and subsequent CPB at Children's Medical Center of Dallas from January 1, 2007 until November 30, 2010 were identified, looking specifically at bi-directional Glenn (BDG) anastomoses and Fontan procedures. One hundred thirteen patients undergoing PCC ≤ 48 hr prior to and > 5 days prior to CPB were included. Occurrence of AKI following CPB was the primary outcome variable.

RESULTS

Logistic regression analysis revealed pre-catheterization serum creatinine was a risk factor for post-CPB AKI (P < 0.001) in both Fontan and BDG patients. All other variables were not significantly associated with the development of AKI in either BDG or Fontan patients. Length of stay (hospital or ICU) was not different among the groups regardless of the occurrence of AKI.

CONCLUSIONS

In this study of cyanotic CHD patients, contrast administration within 48 hr prior to CPB was not an additional risk factor for the development of AKI.

Pre- and/or postnatal protein restriction in rats impairs learning and motivation in male offspring

Suboptimal developmental environments program offspring to lifelong health complications including affective and cognitive disorders. Little is known about the effects of suboptimal intra-uterine environments on associative learning and motivational behavior. We hypothesized that maternal isocaloric low protein diet during pregnancy and lactation would impair offspring associative learning and motivation as measured by operant conditioning and the progressive ratio task, respectively. Control mothers were fed 20% casein (C) and restricted mothers (R) 10% casein to provide four groups: CC, RR, CR, and RC (first letter pregnancy diet and second letter lactation diet), to evaluate effects of maternal diet on male offspring behavior. Impaired learning was observed during fixed ratio-1 operant conditioning in RC offspring that required more sessions to learn vs. the CC offspring (9.4±0.8 and 3.8±0.3 sessions, respectively, p<0.05). Performance in fixed ratio-5 conditioning showed the RR (5.4±1.1), CR (4.0±0.8), and RC (5.0±0.8) offspring required more sessions to reach performance criterion than CC offspring (2.5±0.5, p<0.05). Furthermore, motivational effects during the progressive ratio test revealed less responding in the RR (48.1±17), CR (74.7±8.4), and RC (65.9±11.2) for positive reinforcement vs. the CC offspring (131.5±7.5, p<0.05). These findings demonstrate negative developmental programming effects due to perinatal isocaloric low protein diet on learning and motivation behavior with the nutritional challenge in the prenatal period showing more vulnerability in offspring behavior.

The effects of chronic methylphenidate administration on operant test battery performance in juvenile rhesus monkeys

Methylphenidate (MPH) is an amphetamine derivative widely prescribed for the treatment of attention deficit-hyperactivity disorder. Recent concern over its genotoxic potential in children [11] spurred a study on the effects of chronic MPH treatment in a nonhuman primate population and the studies reported here were conducted in conjunction with that study in the same animals. Here, the focus was on the ability of juvenile rhesus monkeys to learn how to perform a battery of operant behavioral tasks while being treated chronically with MPH. Performance of the National Center for Toxicological Research (NCTR) Operant Test Battery (OTB) was used to quantify the learning of tasks thought to model specific aspects of cognitive function including learning, motivation, color and position discrimination, and short-term memory. The OTB tasks designed to assess these specific behaviors included Incremental Repeated Acquisition (IRA), Progressive Ratio (PR), Conditioned Position Responding (CPR), and Delayed Matching-to-Sample (DMTS), respectively. Juvenile males (n=10/group) pressed levers and press-plates for banana-flavored food pellets. Subjects were treated orally, twice a day, five days per week (M-F) for 66 weeks with escalating doses (0.15 mg/kg initially, increased to 2.5 mg/kg for the low dose group and to 12.5 mg/kg for the high dose group) and tested in OTB tasks 30 to 60 min after the morning dose. The findings indicate that MPH at doses up to 2.5 mg/kg twice per day were well tolerated (performance was no different than controls) but at doses of 12.5 mg/kg twice per day there was a significant decrement in OTB performance, characterized by decreases in both percent task completed and response rates for all tasks. These effects of MPH seem primarily due to decreases in motivation to perform for food, which is not surprising given the well known appetite suppressing effects of amphetamine-like stimulants. Thus, the current data do not strongly suggest cognitive impairments following chronic MPH administration.

Induction of tolerance in renal transplantation using splenic transplantation: experimental study in a canine model

OBJECTIVE

To evaluate in a canine model the induction of tolerance to renal transplantation after splenectomy and splenosis.

MATERIALS AND METHODS

This prospective, experimental, comparative, longitudinal study included 4 experimental groups, each comprising 4 dogs. Group 1 (control group) underwent renal transplantation only; group 2 underwent renal transplantation and splenectomy; group 3 underwent renal transplantation and splenosis; and group 4 underwent renal transplantation, splenectomy, and splenosis. Survival and degree of rejection were compared between the 4 groups.

RESULTS

Splenosis improved renal function after transplantation, as indicated by increased serum creatinine concentration (group 3, 6.2 mg/dL vs group 1, 12.9 mg/dL). Comparison of weighted survival curves (corrected for degree of rejection) demonstrated a significant difference between group 2 (66.0 days) and group 4 (66.2 days) vs group 1 (52.7 days) and group 3 (41.2 days) (P = .05, Wilcoxon rank sum test).

CONCLUSION

These results suggest that in this experimental model of renal transplantation, splenosis and splenectomy induce clinical tolerance, as indicated by improved renal function and prolonged recipient survival.

Modulation of matrix Ca2+ content by the ADP/ATP carrier in brown adipose tissue mitochondria. Influence of membrane lipid composition

The role of the adenine nucleotide translocase on Ca2+ homeostasis in mitochondria from brown adipose tissue was examined. It was found that in mitochondria incubated with 50 microM Ca2+, ADP was not needed to retain the cation, but it was required for strengthening the inhibitory effect of cyclosporin on membrane permeability transition as induced by menadione. In addition, carboxyatractyloside was unable to promote matrix Ca2+ release, even though it inhibits the ADP exchange reaction. However, when the Ca2+ concentration was increased to 150 microM carboxyatractyloside did induce Ca2+ release, and ADP favored Ca2+ retention. Determination of cardiolipin content in the inner membrane vesicles showed a greater concentration in brown adipose tissue mitochondria than that found in kidney mitochondria. It suggested that the failure of the adenine nucleotide translocase to influence membrane permeability transition depends on the lipid composition of the inner membrane.