Wrestling with the complexity of evaluation for organizations at the boundary of science, policy, and practice.

Boundary organizations are situated between science, policy, and practice and have a goal of supporting communication and collaboration among these sectors. They have been promoted as a way to improve the effectiveness of conservation efforts by building stronger relationships between scientists, policy makers, industry, and practitioners (Cook et al. 2013). Although their promise has been discussed in theory, the work of and expectations for boundary organizations are less defined in practice. Biodiversity conservation is characterized by complexity, uncertainty, dissent, and tight budgets, so boundary organizations face the challenging task of demonstrating their value to diverse stakeholders. We examined the challenges boundary organizations face when seeking to evaluate their work and thus aimed to encourage more productive conversations about evaluation of boundary organizations and their projects. Although no off-the-shelf solution is available for a given boundary organization, we identified 4 principles that will support effective evaluation for boundary organizations: engage diverse stakeholders, support learning and reflection, assess contribution to change, and align evaluation with assumption and values.

Iatrogenic kwashiorkor after distal gastric bypass surgery: the consequences of receiving multinational treatment.

Protein-calorie malnutrition or kwashiorkor is extremely rare after gastric bypass surgery. We report a case of a woman referred to a weight management clinic in the United Kingdom who developed bilateral leg oedema 2 years after gastric bypass surgery in Tunisia. Her serum albumin concentration was 24 g/l, and her body mass index was 16.2 kg/m(2). A review of the postoperative report of her bariatric surgery revealed that she had undergone a distal bypass with anastomosis of the intestine at 1 m proximal to the ileocaecal valve. She required gastrostomy feeding for 6 months before undergoing revisional surgery to a proximal Roux-en-Y gastric bypass in order to restore healthy weight. We recommend that if patients are having their bariatric surgery outside of their country of residence, they should always obtain a copy of the operative notes so that these are readily available if complications arise.

Presentation of clinically suspected persistent chlamydial infection: a case series.

In vivo antimicrobial resistance has yet to be documented in Chlamydia trachomatis; however, there have been anecdotal reports of persistent infection. The purpose of this case series was to describe a group of patients who have persistent chlamydia infection despite adequate treatment and where re-infection was considered unlikely. Patients were selected using a clinical questionnaire. For inclusion patients had to have tested positive for C. trachomatis, at least twice, using a nucleic acid amplification test despite having been fully compliant with at least two rounds of recommended therapy and be deemed to be at low risk of re-infection. Patients were grouped into categories based on sexual behaviour. Twenty-eight patients are included in this case series; 46% declared no sexual contact since initial diagnosis (category 1), a further 36% declaring contact that was considered low risk of re-infection (categories 2-4); 61% showed signs and symptoms at initial presentation increasing to 75% at re-attendance. Thirty-nine percent of patients received azithromycin only while 48% received doxycycline also. This case series identifies patients with persistent chlamydia despite receiving treatment. There is a need for a case definition of clinical treatment failure, development of susceptibility testing methods and guidance on appropriate treatment for patients with persistent infection.

Use of in vitro gas production models in ruminal kinetics.

Physiological systems models for ruminant animals are used to predict the extent of ruminal carbohydrate digestion, based on rates of intake, digestion, and passage to the lower tract. Digestion of feed carbohydrates is described in these models by a first-order rate constant. Recently, an in vitro gas production technique has been developed to determine the digestion kinetics in batch fermentation, and nonlinear mathematical models have been fitted to the cumulative gas production data from these experiments. In this paper, we present an analysis that converts these gas production models to an effective first-order rate constant that can be used directly in rumen systems models. The analysis considers the digestion of an incremental mass of substrate entering the rumen. The occurrence of passage is represented probabilistically, and integration through time gives the total mass of substrate and total rate of digestion in the rumen. To demonstrate the analysis, several gas production models are fitted to a sample data set for corn silage, and the effective first-order rate constants are calculated. The rate constants for digestion depend on ruminal passage rate, an interaction that arises from the nonlinearity of the gas production models.

Depth of insertion at flexible sigmoidoscopy: implications for colorectal cancer screening and instrument design.

BACKGROUND AND STUDY AIMS: The depth of insertion at flexible sigmoidoscopy is variable, depending upon bowel preparation, patient tolerance and distal colonic anatomy. Many endoscopists routinely aim to insert the 60 cm flexible sigmoidoscope to the splenic flexure; however internal endoscopic markers are unreliable, making the true anatomical extent of the examination difficult to assess. The aim of this study was to assess the depth of insertion at flexible sigmoidoscopy. PATIENTS AND METHODS: Two separate studies were done. In the first (study 1), magnetic endoscopic imaging was used to determine the final depth of insertion at non-sedated, screening flexible sigmoidoscopy. In the second (study 2), "real-time" imaging was utilized to determine sigmoid looping and the anatomical location of the endoscope tip after 60 cm of instrument had been inserted during total or limited colonoscopy. A total of 117 consecutive average-risk patients, aged 55-65 years participated in study 1, and 136 patients underwent either limited, (33) or attempted total colonoscopy (103) in study 2. RESULTS: In study 1 the median insertion distance was 52 cm, range 20-58. In 61 % of patients the imaging system showed that the descending colon had not been visualized by the end of the procedure. Failure to reach the sigmoid/descending junction occurred in 29 (24%) patients. Reasons for failure included poor tolerance of the procedure due to pain (23 patients) inadequate preparation (3 patients) and, excessive looping (3 patients). In study 2, after 60 cm of instrument had been inserted, the splenic flexure or beyond was reached in 29% and the descending colon in 9%, whilst in 62 % the endoscope tip had not passed beyond the sigmoid/descending colon junction. A sigmoid loop formed in 70% of patients, and unusual loops such as the alpha, reverse alpha and reverse sigmoid spiral loop occurred more frequently in women compared to men (P = 0.0249). In those 104 patients where the splenic flexure was reached the mean maximum length of instrument inserted prior to reaching the flexure was 75.4 cm, (SD = 21.9). CONCLUSIONS: Examination of the entire sigmoid was not achieved in approximately one-quarter of patients undergoing screening flexible sigmoidoscopy, mainly because of discomfort. The descending colon is intubated in a minority of cases (using standard instruments), even after 60 cm has been inserted. Alternative instruments with different shaft characteristics (floppy, narrow calibre, 80-100 cm in length) may be necessary to ensure deeper routine intubation in nonsedated patients.

Fractal-based image texture analysis of trabecular bone architecture.

Fractal-based image analysis methods are investigated to extract textural features related to the anisotropic structure of trabecular bone from the X-ray images of cubic bone specimens. Three methods are used to quantify image textural features: power spectrum, Minkowski dimension and mean intercept length. The global fractal dimension is used to describe the overall roughness of the image texture. The anisotropic features formed by the trabeculae are characterised by a fabric ellipse, whose orientation and eccentricity reflect the textural anisotropy of the image. Tests of these methods with synthetic images of known fractal dimension show that the Minkowski dimension provides a more accurate and consistent estimation of global fractal dimension. Tests on bone x-ray (eccentricity range 0.25-0.80) images indicate that the Minkowski dimension is more sensitive to the changes in textural orientation. The results suggest that the Minkowski dimension is a better measure for characterising trabecular bone anisotropy in the x-ray images of thick specimens.

Modeling ruminal pH fluctuations: interactions between meal frequency and digestion rate.

A steady periodic analysis of ruminal carbohydrate digestion was developed to predict the effects of diet and frequency of eating on ruminal pH fluctuation. Tests of the model against previous data showed that pH fluctuations were too large when previously published rates of carbohydrate digestion were used but were improved using rates from an in vitro gas production system, which were lower. With the original digestion rates, the minimum meal frequency to maintain steady-state conditions in the rumen increased from 4 to 12 meals/d as dietary effective neutral detergent fiber (NDF) decreased from 34 to 6% of dry matter (DM); with the revised rates, the minimum frequency was 3 to 6 meals/d, respectively. The minimum effective NDF to maintain a pH value above 6.0 increased from 14 to 23% of DM as meal frequency decreased from steady state to 2 meals/d using the original rates; with the revised rates, the minimum effective NDF was slightly smaller, increasing from 13 to 21% of DM, respectively. Effects of DM intake and body weight on pH fluctuation were minor, and dietary buffers, when used at rates less than 1%, did not reduce fluctuation. Different methods of calculating mean ruminal pH yielded different results for the effect of meal frequency on mean pH.

Prediction of ruminal volatile fatty acids and pH within the net carbohydrate and protein system.

A steady-state model of the production, absorption, passage, and concentration of ruminal VFA and pH is developed from published literature data and is structured to use the feed descriptions and inputs from the net carbohydrate and protein system. Included are the effects of pH on growth rate and yield of structural and non-structural carbohydrate-fermenting bacteria; production of acetate, propionate, butyrate, lactate, and methane; conversion of lactate to VFA; ruminal absorption of acids; and prediction of ruminal pH from dietary measures and from ruminal buffering and acidity. The root mean square error of predicted total VFA concentration was 12 mM. Individual VFA fractions were inadequately predicted. In a review of literature data, effective NDF (eNDF) provided a better correlation with ruminal pH than forage or NDF. Digestion rate of NDF remained at normal levels above pH 6.2, which corresponds to a minimum eNDF of 20% of dietary DM. Further research is needed to determine the individual VFA produced from carbohydrate fractions at various pH, the appropriateness of partitioning the starch and pectin carbohydrate pool into slowly and rapidly degraded fractions, and the effect on microbial yield, total tract digestibility, and predicted energy values of feeds.

Application of the Cornell Net Carbohydrate and Protein model for cattle consuming forages.

Accurate prediction of forage biological values and performance with animals fed forages requires accurately accounting for factors that influence animal requirements and feedstuff utilization. The Cornell Net Carbohydrate and Protein System (CNCPS) is an application model that uses a combination of mechanistic and empirical approaches to account for the effects of variation in animal factors and feed carbohydrate and protein fractions on animal performance. Thus, accurate animal and environmental descriptions, DMI, feed carbohydrate, and protein fractions and their digestion rates are required inputs. In 25 growth periods with calves fed high-forage diets, the CNCPS accounted for 74, 81, and 83%, respectively, of the variation in ADG predicted to be supported by the ME, metabolizable protein, and essential amino acid intake, the first-limiting of all three accounting for 81% of the variation with a -1% bias. Thus, the CNCPS can be used to accurately describe forage quality and the effects of changes in forage composition on animal performance. The model was sensitive to variations in NDF, CP, protein solubility, NDF and starch digestion rates, feed and microbial amino acid composition, maintenance protein requirement, body protein amino acid content, and the coefficient of efficiency of use of absorbed protein. Analysis of several trials indicates an improved efficiency of ME use with improved amino acid balances. Uses of the CNCPS discussed include interpreting, planning and applying research, teaching, developing tables of requirements and biological values for feeds, complex nutritional accounting, and predicting performance and profits.

Kinetics of fiber digestion from in vitro gas production.

In vitro gas production, measured by computer-interfaced pressure sensors, was used to follow the digestion of a crystalline processed cellulose, a bacterial cellulose, and mixtures of these substrates by mixed ruminal bacteria. A first-order, substrate limited model (simple exponential with lag) and two bacterial growth models (logistic, Gompertz) were tested to fit these data. No single pool model gave an optimal fit to all substrates, but dual pool versions of both the logistic and Gompertz models fitted the data extremely well. Derivations of these models in the context of gas production are presented. The dual pool version of the exponential model commonly used to analyze fiber digestion was not able to reproduce the slope variations seen with mixed substrates. A modified dual pool logistic equation, with a single lag value, was selected to model the in vitro digestion of these substrates. The model was able to predict adequately both the input composition and the kinetic parameters for a defined mixture and gave a good fit (r2 > .995) to data from all the single and mixed substrates tested. This model may be useful for interpreting gas accumulation from natural feedstuffs.

Osmometric behavior, hydraulic conductivity, and incidence of intracellular ice formation in bovine oocytes at different developmental stages.

Bovine oocytes that were immature (IMM), matured in vitro (IVM) or in vivo (MAT), or matured and fertilized in vitro (IVF) were studied using a microscope diffusion chamber to estimate osmotic parameters and a cryomicroscope to characterize intracellular ice formation (IIF). Linear Boyle van't Hoff relationships were observed with all four types of oocytes between 0.265 and 0.799 osm NaCl. At 20 degrees C, estimates of hydraulic conductivity (Lp) were significantly higher for IVM oocytes than IMM and MAT oocytes (0.84 micron/(min.atm) vs 0.45 and 0.47, respectively). IVM oocytes also tended to have higher Lp values than IVF oocytes (0.55 micron/(min.atm)). At 5 degrees C, the Lp of IVM oocytes decreased to 0.36 micron/min.atm) corresponding to an Arrhenius activation energy of 7.84 kcal/mol. The incidence of IIF in MAT oocytes suspended in salt solution and subjected to linear cooling to -60 degrees C was 45% at 4 degrees C/min, 75% at 8 degrees C/min, and 93% at 16 degrees C/min; with IVF oocytes, the incidence of IIF was 40% at 4 degrees C/min, 92% at 8 degrees C/min, and 100% at 16 degrees C/min. Comparisons involving median IIF temperatures (TIIF50s) and the distributions of the observed IIF temperatures for IMM (Myers et al., Cryo-Lett. 8, 260), IVM (Chandrasekaran et al., Cryobiology 27, 676), MAT and IVF oocytes indicated that the IIF incidence in IMM oocytes cooled at 4 degrees C/min was greater than that of oocytes at the other developmental stages cooled at the same rate. The TIIF50s of IVM and IVF oocytes were lowered by equilibration in 1.5 M ethylene glycol (EG), glycerol, or propylene glycol (PG) prior to cooling, with EG tending to lower the TIIF50s more than glycerol or PG. For all three cryoprotectants, the TIIF50s and IFF temperature distributions were cooling-rate dependent. The Weibull probability distribution was fitted to the distributions of the IIF temperatures of oocytes suspended in salt solutions with and without cryoprotectants yielding R2 values ranging from 0.70 to 0.98.

A Descriptive Model of Mold Growth and Aflatoxin Formation as Affected by Environmental Conditions.

A model is presented which integrates literature data on the effects of temperature, water activity, pH, and colony size on mold growth and aflatoxin formation. Mathematical forms for the rates of growth and toxin formation are based on assumptions about the biology of toxigenesis. The rate of toxin formation is assumed to be proportional to the rate of production of new cell mass, and the rate of toxin degradation is assumed to be proportional to the product of the concentrations of dead cell mass and aflatoxin; the latter assumption is an attempt to be consistent with the notion that toxin degradation is effected by enzymes released during mycelial lysis. Growth rate and toxin yield are represented by a maximum or reference value times a series of factors dependent on environmental conditions. Temperature and water activity have an interactive effect on growth and toxigenesis in the model. An Arrhenius-like function is postulated for the effects of temperature; shape parameters in the function are selected assuming that optimum temperature bears a fixed relationship to temperature limits for growth and toxigenesis, which vary with water activity. A linear function is postulated for the effect of water activity, with the lower limit dependent on temperature. Parabolic and Monod models are used to describe the effects of pH and colony size, respectively. Toxigenic parameters are estimated by comparing model simulations to the results of two published studies, with fair consistency in the two sets of parameters. In comparisons with other studies, the model did not correctly project the effects of spore load, but did correctly predict toxigenic behaviors relating to the effects of temperature and temperature cycling. The model provides a theoretical explanation for observed temporal shifts in the optimum temperature for toxigenesis, and for a hyperbolic relationship between heat units and time to toxigenesis with and without temperature cycling.

Dynamic model prediction of the value of reduced solubility of alfalfa silage protein for lactating dairy cows.

A net carbohydrate and protein system was used to develop model diets for lactating dairy cattle with various protein solubilities in the alfalfa silage component of the diet. The objective was to determine the level to which alfalfa silage could be used to replace supplemental protein sources as the silage protein solubility decreased and to estimate the value of silage treatments needed to reduce protein solubility. Four cow groups were considered: early lactation multiparous cows, primiparous cows, midlactation cows, and late lactation cows. Diets were balanced for metabolizable protein, metabolizable energy, and ammonia and peptides for rumen bacteria; limits on DMI and effective NDF were enforced. Lower protein solubility was predicted to increase the yield of bacteria per unit of alfalfa silage DM and the yield of metabolizable protein per unit of alfalfa silage CP. Because of reduced protein supplements, diet costs were decreased. The savings per unit of silage in these rations increased as alfalfa silage protein solubility decreased. For example, with a reduction in solubility from 61 to 51% of CP, the savings ranged from $2.96 to $3.26/tonne of silage across the four cow groups. The value of acid treatment of silage needed to effect these reductions exhibited diminishing returns as application rate increased and appeared to be most cost effective when used on high quality alfalfa fed to high producing cows with application rates less than 2 kg/tonne. Management practices that reduce silage temperatures were predicted to save $.50 to $1.50/tonne of silage when the diets were balanced to account for protein degradability.

Performance of a kinetic model for intracellular ice formation based on the extent of supercooling.

Cryomicroscopy was used to study the incidence of intracellular ice formation (IIF) in protoplasts isolated from rye (Secale cereale) leaves during subfreezing isothermal periods and in in vitro mature bovine oocytes during cooling at constant rates. IIF in protoplasts occurred at random times during isothermal periods, and the kinetics of IIF were faster as isothermal temperature decreased. Mean IIF times decreased from approximately 1700 s at -4.0 degrees C to less than 1 s at -18.5 degrees C. Total incidence of IIF after 200 s increased from 4% at -4.0 degrees C to near 100% at -15.5 degrees C. IIF behavior in protoplasts was qualitatively similar to that for Drosophila melanogaster embryos over the same temperature ranges (Myers et al., Cryobiology 26, 472-484, 1989), but the kinetics of IIF were about five times faster in protoplasts. IIF observations in linear cooling of bovine oocytes indicated a median IIF temperature of -11 degrees C at 16 degrees C/min and total incidences of 97%, 50%, and 19% at 16, 8, and 4 degrees C/min, respectively. A stochastic model of IIF was developed which preserved certain features of an earlier model (Pitt et al. Cryobiology 28, 72-86, 1991), namely Weibull behavior in IIF temperatures during rapid linear cooling, but with a departure from the concept of a supercooling tolerance. Instead, the new model uses the osmotic state of the cell, represented by the extent of supercooling, as the independent variable governing the kinetics of IIF. Two kinetic parameters are needed for the model: a scale factor tau 0 dictating the sensitivity to supercooling, and an exponent rho dictating the strength of time dependency. The model was fit to the data presented in this study as well as those from Myers et al. and Pitt et al. for D. melanogaster embryos with and without cryoprotectant, and from Toner et al. (Cryobiology 28, 55-71, 1991) for mouse oocytes. In protoplasts, D. melanogaster embryos, and mouse oocytes, the parameters were estimated from IIF times in the early stages of isothermal periods, while the osmotic state of the cell was relatively constant. In bovine oocytes, the parameters were estimated from linear cooling data. Without further calibration, the model was used to predict total IIF incidence under different cooling regimes. For protoplasts, D. melanogaster embryos, and bovine oocytes, the model's predictions were quite accurate compared to the actual data. In mouse oocytes, adjustment of the hydraulic permeability coefficient (Lp) at 0 degree C was required to yield realistic behavior.(ABSTRACT TRUNCATED AT 400 WORDS)

A tungsten-supplemented diet delivered by transplacental and breast-feeding routes lowers intestinal xanthine oxidase activity and affords cytoprotection in ischemia-reperfusion injury to the small intestine.

Ischemia-reperfusion injury has been implicated as playing a major role in the development of necrotizing enterocolitis, a major cause of morbidity and mortality in the newborn. A tungsten-supplemented molybdenum-free diet can reduce xanthine oxidase (XO) enzyme activity in the intestine, which in turn reduces the generation of oxygen radicals after an ischemia-reperfusion insult. This study evaluated the ability of this diet to be effective by indirect means, ie, transplacental and breast-feeding routes. XO activity of the intestine was measured in three groups of CD-1 white rats: I, weanlings fed the tungsten diet or standard chow for 1 week; II, 1-day-old rat pups whose mothers were maintained on the tungsten or standard chow for 7 to 10 days prior to term; and III, rat pups at 1 and 3 weeks after birth whose lactating mothers were maintained on the tungsten or standard chow. Some animals from group III also underwent either a 30- or 60-minute episode of occlusion of the superior mesenteric artery (SMA) to evaluate the protective effects of the diet. XO activity was significantly reduced in all groups receiving the tungsten diet (P less than .0001). Blinded histopathologic studies of the entire small bowel showed significantly less villar necrosis (P less than .05) and fibrosis (P less than .0001) in the tungsten-treated group than in the controls. In the 60-minute occlusion study all tungsten-group animals survived, whereas 7 of 12 in the control group died of intestinal infarction within 24 hours (P less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Subfreezing volumetric behavior and stochastic modeling of intracellular ice formation in Drosophila melanogaster embryos.

Cryomicroscopic observations were made of the volumetric behavior and kinetics of intracellular ice formation (IIF) in Drosophila melanogaster embryos in a modified cell culture medium (BD.20) or BD.20 + 2 M ethylene glycol. After rapid cooling to a given temperature, transient volumetric contraction of the embryos during the isothermal period was quantified by computerized video image analysis. Fitting these data to the numerical solution of the volume flux equation yielded estimates of the hydraulic permeability coefficient (Lp) for individual embryos at various subfreezing temperatures. Lp approximately followed an Arrhenius relation between -2 and -9 degrees C, with a value of 0.168 microns/(min-atm) extrapolated to 0 degrees C and an apparent activation energy delta E of 38.9 kcal/mol. IIF during an isothermal period occurred at random times whose characteristic temperature range and kinetics were affected by the presence of ethylene glycol. A stochastic process model developed to fit these data indicated the influence of both time-dependent and instantaneous components of IIF, presumed to be the result of seeding and heterogeneous nucleation, respectively. The presence of 2 M ethylene glycol depressed the characteristic temperature of instantaneous IIF by about 12 degrees C and reduced the rate constant for time-dependent IIF. Comparison with observed incidences of IIF yielded an estimate of the supercooling tolerance of 3 to 5 degrees C.