Stable carbon and nitrogen isotopes explain methylmercury concentrations in stream food webs of Lake George, New York (USA).

Mercury has been studied extensively in lakes due to health risks associated with the consumption of contaminated fish, while stream ecosystems have received less attention. To better understand mercury bioavailability in the lower food web of streams, we collected macroinvertebrates (predators and detritivore) along with autochthonous (epilithic algae) and allochthonous (leaf litter) basal resources in eight streams entering Lake George. Samples were analyzed for methylmercury (MeHg), total mercury, and carbon and nitrogen isotopes (δ13C & δ15N) to determine how mercury concentrations in basal resources, biomagnification rates, and environmental factors (watershed characteristics and water chemistry) effected MeHg concentrations in predatory macroinvertebrates. While biomagnification rates, calculated as trophic magnification slope, explained between 68% and 98% of MeHg variability within a stream food web, the range was small (0.310-0.387) resulting in the biotic components following a consistent pattern of increasing MeHg among streams. The stream order was negatively related to basin slope for all biotic components and explained 70% of MeHg variability in predatory macroinvertebrates. Methylmercury concentrations were significantly and negatively related to δ13C in predators, epilithic algae, and leaf litter. We believe the biofilms on leaf litter utilized bacterial-respired carbon dioxide decreasing δ13C (<-28‰) and increasing MeHg while epilithic algal δ13C increased due to enhanced primary production resulting in biodilution of MeHg. Methylmercury in basal resources responded to δ13C similarly but through different processes. Our findings show shallow slopes elevate MeHg in basal resources and explain most of the predator MeHg variation among streams with little influence of biomagnification rates.

An examination of mercury levels in the coastal environment and fish of Cote d'Ivoire.

Artisanal and small-scale gold mining (ASGM), energy production and other industrial inputs are a major source of anthropogenic mercury (Hg) to the aquatic environment globally, and these inputs have led to environmental contamination and human exposure. While studies have documented the effects of Hg inputs to rivers and marine waters of the West African region, estuarine waters of Cote d'Ivoire have been understudied, besides the waters surrounding Abidjan. To fill this gap, and to examine the potential for human exposure to methylmercury (MeHg), we measured the concentrations of total Hg, MeHg, and ancillary parameters in water (dissolved and particulate phases), sediment and fish to determine the extent of environmental impact and the potential for MeHg exposure for people consuming these fish. Levels of Hg and MeHg in sediment were elevated in the vicinity of the urban environment (up to 0.3 ng/g dry weight (dw) MeHg and 623 ng/g dw total Hg) and lowest in the more remote estuarine environments. Measurements of Hg in tuna and other larger pelagic coastal species indicated that levels were elevated but comparable to other North Atlantic regions. However, levels of Hg in fish, even smaller estuarine species, were such that the rural and urban populations are potentially being exposed to unsafe levels of MeHg, primarily as a result of the relatively high fish consumption in Cote d'Ivoire compared to other countries. Overall, both local point sources and the transport of Hg used in interior ASGM activities are the sources for Hg contamination to these coastal waters.

Feeding an acetate-based oral electrolyte reduces the ex vivo Escherichia coli growth potential in the abomasum of calves fed oral electrolytes alone or 30 minutes following a milk feeding compared with feeding a bicarbonate-based oral electrolyte.

Oral electrolyte solutions (OES) are a common, on-farm therapy to reestablish hydration and electrolyte balances in scouring and stressed calves. The objectives were to determine the effects of OES alkalinizing agent and the presence of a milk replacer feeding before OES administration on the abomasal environment in healthy Holstein calves. Abomasum cannulation was performed on 16 Holstein bull calves at 5 d of age. One calf was removed from the study before the calves were randomly assigned to treatments at 9 d of age. Treatments were arranged as a 2-by-2 factorial, with the following factors: oral electrolyte alkalinizing agent [acetate (A) or bicarbonate (B)] and liquid meal type milk replacer (MR) + OES (MR-A, MR-B), or OES only (OES-A, OES-B)]. The OES differed only by alkalinizing agent. On d 9, calves assigned to MR-A (n = 4) or MR-B (n = 4) received their morning MR aliquot 0.5 h before feeding 2 L of OES; the OES-A (n = 3) and OES-B (n = 4) treatment groups were fed 2 L of OES only. Peripheral blood samples and postprandial abomasal fluid samples were collected to assess abomasal pH, abomasal emptying rate (AER), and ex vivo abomasal Escherichia coli growth potential. Postprandial pH was greater in calves fed MR or B-based OES. Abomasal emptying rate was slower in calves receiving MR + OES, regardless of the alkalinizing agent. Ex vivo E. coli colony-forming unit counts were greater in calves fed either MR + OES or bicarbonate-based OES. Supplementing bicarbonate OES in addition to MR alters abomasal dynamics and may promote E. coli growth in postprandial abomasal fluid, partially due to sustained elevations in gastric pH and delayed gastric emptying rates. The OES containing sodium acetate limited ex vivo E. coli growth potential in abomasal fluid, thereby potentially reducing the risk of additional enteric bacterial complications associated with OES therapy.

Analysis of the gut bacterial communities in beef cattle and their association with feed intake, growth, and efficiency.

The impetus behind the global food security challenge is direct, with the necessity to feed almost 10 billion people by 2050. Developing a food-secure world, where people have access to a safe and sustainable food supply, is the principal goal of this challenge. To achieve this end, beef production enterprises must develop methods to produce more pounds of animal protein with less. Selection for feed-efficient beef cattle using genetic improvement technologies has helped to understand and improve the stayability and longevity of such traits within the herd. Yet genetic contributions to feed efficiency have been difficult to identify, and differing genetics, feed regimens, and environments among studies contribute to great variation and interpretation of results. With increasing evidence that hosts and their microbiomes interact in complex associations and networks, examining the gut microbial population variation in feed efficiency may lead to partially clarifying the considerable variation in the efficiency of feed utilization. The use of metagenomics and high-throughput sequencing has greatly impacted the study of the ruminant gut. The ability to interrogate these systems at great depth has permitted a greater understanding of the microbiological and molecular mechanisms involved in ruminant nutrition and health. Although the microbial communities of the reticulorumen have been well documented to date, our understanding of the populations within the gastrointestinal tract as a whole is limited. The composition and phylogenetic diversity of the gut microbial community are critical to the overall well-being of the host and must be determined to fully understand the relationship between the microbiomes within segments of the cattle gastrointestinal tract and feed efficiency, ADG, and ADFI. This review addresses recent research regarding the bacterial communities along the gastrointestinal tract of beef cattle; their association with ADG, ADFI, and feed efficiency; and the potential implications for beef production.

Microbial community profiles of the jejunum from steers differing in feed efficiency.

Research regarding the association between the microbial community and host feed efficiency in cattle has primarily focused on the rumen. However, the various microbial populations within the gastrointestinal tract as a whole are critical to the overall well-being of the host and need to be examined when determining the interplay between host and nonhost factors affecting feed efficiency. The objective of this study was to characterize the microbial communities of the jejunum among steers differing in feed efficiency. Within 2 contemporary groups of steers, individual ADFI and ADG were determined from animals fed the same diet. At the end of each feeding period, steers were ranked based on their standardized distance from the bivariate mean (ADG and ADFI). Four steers with the greatest deviation within each Cartesian quadrant were sampled ( = 16/group; 2 groups). Bacterial 16S rRNA gene amplicons were sequenced from the jejunum content using next-generation sequencing technology. The phylum Firmicutes accounted for up to 90% of the populations within all samples and was dominated by the families Clostridiaceae and Ruminococcaceae. UniFrac principal coordinate analyses did not indicate any separation of microbial communities within the jejunum based on feed efficiency phenotype, and no significant changes were indicated by bacterial diversity or richness metrics. The relative abundances of microbial populations and operational taxonomic units did reveal significant differences between feed efficiency groups ( < 0.05), including the phylum Proteobacteria ( = 0.030); the families Lachnospiraceae ( = 0.035), Coriobacteriaceae ( = 0.012), and Sphingomonadaceae ( = 0.035); and the genera ( = 0.019), ( = 0.018), and ( = 0.022). The study identified jejunal microbial associations with feed efficiency, ADG, and ADFI. This study suggests the association of the jejunum microbial community as a factor influencing feed efficiency at the 16S level.

Cecum microbial communities from steers differing in feed efficiency.

Apart from the rumen, limited knowledge exists regarding the structure and function of bacterial communities within the gastrointestinal tract and their association with beef cattle feed efficiency. The objective of this study was to characterize the microbial communities of the cecum among steers differing in feed efficiency. Within 2 contemporary groups of steers, individual feed intake and BW gain were determined from animals fed the same diet. Within both of 2 contemporary groups, BW was regressed on feed intake and 4 steers within each Cartesian quadrant were sampled ( = 16/group). Bacterial 16S rRNA gene amplicons were sequenced from the cecal content using next-generation sequencing technology. No significant changes in diversity or richness were detected among quadrants, and UniFrac principal coordinate analysis did not show any differences among quadrants for microbial communities within the cecum. The relative abundances of microbial populations and operational taxonomic units revealed significant differences among feed efficiency groups ( < 0.05). Firmicutes was the dominant cecal phylum in all groups and accounted for up to 81% of the populations among samples. Populations were also dominated by families Ruminococcaceae, Lachnospiraceae, and Clostridiaceae, with significant shifts in the relative abundance of taxa among feed efficiency groups, including families Ruminococcaceae ( = 0.040), Lachnospiraceae ( = 0.020), Erysipelotrichaceae ( = 0.046), and Clostridiaceae ( = 0.043) and genera ( = 0.049), ( = 0.044), ( = 0.042), ( = 0.040), ( = 0.042), and ( = 0.042). The study identified cecal microbial associations with feed efficiency, ADG, and ADFI. This study suggests an association of the cecum microbial community with bovine feed efficiency at the 16S level.

Methane production and methanogen levels in steers that differ in residual gain.

Methane (CH4) gas released by cattle isa product of fermentation in the digestive tract. The 2 primary sites of CH4 production in ruminants are the reticulum-rumen complex and the cecum. Methane release from cattle represents a 2% to 12% loss of the energy intake. Reducing the proportion of feed energy lost as CH4 has the potential of improving feed efficiency as well as decreasing the contribution of cattle to greenhouse gas production. Feed intake and growth were measured on 132 fall-born steers for 70 d. Seven steers with extreme positive residual gain (RG) and 7 steers with extreme negative RG whose DMI was within 0.32 SD of the mean intake were selected for subsequent measurements. Enteric CH4 production was measured via indirect calorimetry. Rumen, cecum, and rectal contents were obtained from steers at slaughter for measurement of in vitro CH4 production and methanogen 16S rRNA levels. Enteric CH4 production did not differ (P = 0.11) between the positive RG (112 ± 13 L/d)and the negative RG (74 ± 13 L/d) steers. In vitro rumen methane production did not differ between positive RG(64.26 × 10(-5) ± 10.85 × 10(-5) mmol∙g(-1) DM∙min(-1)) and negative RG (61.49 × 10(-5) ± 10.85 × 10(-5) mmol∙g(-1)DM∙min(-1); P = 0.86). In vitro cecum methane production did not differ between positive RG (4.24 ×10(-5) ± 1.90 × 10(-5) mmol∙g(-1) DM∙min(-1)) and negative RG (4.35 × 10(-5) ± 1.90 × 10(-5) mmol∙g(-1) DM∙min(-1); P = 0.97). Methanogen 16S rRNA as a percentage of the total bacteria16S rRNA did not differ between RG groups (P = 0.18). The methanogen 16S rRNA as a percentage of rumen fluid total bacteria 16S rRNA (5.3% ±3.1%) did not differ from the methanogen 16S rRNA asa percentage of cecum content total bacteria 16S rRNA(11.8% ± 3.1%; P = 0.14). The methanogen 16S rRNA as a percentage of the rectum content total bacteria 16SrRNA (0.7% ± 3.1%) was not different from the rumen content (P = 0.29) but was less than the cecum content(P = 0.01). Methanomicrobiales 16S rRNA as a percentage of total methanogen 16S rRNA did not differ across sample sites (P = 0.81); however, steers with positive RG (10.5% ± 1.6%) were more numerous than steers with negative RG (5.1% ± 1.6%; P = 0.02). Cattle that differ in RG at the same DMI do not differ in characteristics associated with CH4 production.

Guidelines for the pediatric perioperative anesthesia environment. American Academy of Pediatrics. Section on Anesthesiology.

The American Academy of Pediatrics proposes the following guidelines for the pediatric perioperative anesthesia environment. Essential components are identified that make the perioperative environment satisfactory for the anesthesia care of infants and children. Such an environment promotes the safety and wellbeing of infants and children by reducing the risk for adverse events.

Use of beta-hydroxybutyric acid levels in the emergency department.

UNLABELLED: The impact of a new test on the market, the beta-hydroxybutyric acid (BOH) assay, on clinical decision-making in the emergency department (ED) has not been well studied. In this retrospective analysis, we studied the potential benefit of this new test in the ED decision-making process in diabetic patients. BOH levels were measured on all patients who had glucose and acetone levels ordered by the emergency physician during a 3-month period in the ED of a university tertiary referral center. Two groups were analyzed: group 1 was acetone-positive and BOH-positive (n = 13); group 2 was acetone-negative BOH-positive (n = 31). There was no difference between the two groups in terms of gender (p = 0.55) or age (p = 0. 47). The length of stay (p = 0.97) and number of complications (p = 0.89) were also similar between the two groups. CONCLUSION: This study suggests that in those diabetic patients with a negative acetone test and a positive BOH test, the addition of the positive result on the BOH test may provide additional prognostic information for predicting hospital length of stay and number of in-hospital complications.

Serum albumin as a predictor of course and outcome on a rehabilitation service.

To determine the effect of nutritional status on the medical course and rehabilitation outcome of patients on an adult rehabilitation service, serum albumin (SA) and total lymphocyte count (TLC) were prospectively studied on 36 patients. Readings were taken on admission (T-1), at which time a Barthel Index Mobility Goal (BIMG) was assigned, and again 4 to 8 weeks after admission (T-2). A Barthel Index Mobility Score (BIMS) was assigned at discharge. Rehabilitation program restrictions due to medical complications correlated negatively with both the SA level at T1 (r = -.328, p less than 0.05) and at T2 (r = -.523, p less than 0.01). The SA level at T2 correlated positively with the BIMS:BIMG ratio (r = .416, p less than 0.05) at discharge, suggesting that SA levels may predict patient mobility outcome.