bluuebunny/crossref_metadata_2025 huggingface dataset:
Controlling Tailwater Sediment and Phosphorus Concentrations with Polyacrylamide in the Imperial Valley, California
Authors: Goodson Christopher C. , Schwartz Gregory , Amrhein Christopher
Published: June 2006

External loading of phosphorus (P) from agricultural surface discharge (tailwater) is the main cause of excessive algae growth and the eutrophication of the Salton Sea, California. Continuous polyacrylamide (PAM) applications to agricultural irrigation water inflows were evaluated as a means of reducing sediment and P in tailwater. Zero (control) and 1 mg L−1 PAM (PAM1) treatments were compared at 17 Imperial Valley field sites. Five and 10 mg L−1 PAM treatments (PAM5, PAM10) were conducted at one site. The particulate phosphorus (Pp) fraction was determined as the difference between total phosphorus (Pt) and the soluble phosphorus (Ps) fraction. We observed 73, 82, and 98% turbidity reduction with PAM1, PAM5, and PAM10 treatments. Although eight field sites had control tailwater sediment concentrations above the New River total maximum daily loads (TMDL), all but one were made compliant during their paired PAM1 treatments. While PAM1 and PAM10 reduced tail water Pp by 31 and 78%, none of the treatments tested reduced Ps This may have been caused by high irrigation water Na concentrations which would reduce Ca adsorption and Ca‐phosphate bridging on the PAM. The PAM1 treatments resulted in <0.5 mg L−1 drain water polyacrylamide concentrations 1.6 km downstream of PAM addition, while PAM5 and PAM10 treatments produced >2 mg L−1 drain water polyacrylamide concentrations. We concluded that, although PAM practically eliminates Imperial Valley tailwater sediment loads, it does not effectively reduce tailwater Ps, the P fraction most responsible for the eutrophication of the Salton Sea.
Solubility of Antimony and Other Elements in Samples Taken from Shooting Ranges
Authors: Johnson C. Annette , Moench Hermann , Wersin Paul , Kugler Pia , Wenger Christoph
Published: June 2006

The aim of this study was to determine whether or not Sb and other elements (Ni, Cu, Bi, Tl, and Hg) originating from Pb alloy (2–5 wt. % Sb) bullets become more soluble as a result of weathering and what mechanisms possibly control their solubility. Samples were taken from bank material behind the targets at seven Swiss shooting ranges. The samples were dried, sieved, analyzed, and subjected to leaching experiments. Total average concentrations of Sb ranged from 0.5 to 13.8 g kg−1In the leaching experiments, Sb was almost exclusively present in solution as the oxidized species Sb(V) in concentrations of up to 5 mg L−1The Ca mineral Ca[Sb(OH)6]2is suggested to control dissolved Sb(V) concentrations in soils at high concentrations. Oxalate extractions suggested that approximately 50% of Sb [predominantly Sb(V)] in the <0.5‐mm fraction was adsorbed to Fe (hydr)oxides and possibly other minerals, such as calcite, that are soluble at pH 2. However, it is possible that only a fraction of the oxalate‐extractable Sb(V) is reversibly bound to mineral surfaces. It was concluded that the release of Sb is significant and considerably higher than the other elements under investigation and that the mechanisms controlling Sb mobility should be further investigated.
Effect of Organic Amendment and Plant Roots on the Solubility and Mobilization of Lead in Soils at a Shooting Range
Authors: Levonmäki M. , Hartikainen H. , Kairesalo T.
Published: June 2006

Lead (Pb) dissolving gradually from spent pellets constitutes a serious environmental risk in and near shooting ranges, and remediation measures are necessary to prevent its movement to deeper soil layers and ground water. In this study, the effectiveness of organic amendment and plant roots in stabilizing Pb was assessed in a microcosm experiment. Planted (Scots pine, Pinus sylvestris L.) and unplanted microcosms consisting of coarse‐textured mineral soil covered with Pb‐contaminated humic topsoil were coated with uncontaminated peat layers of 1 to 3 cm and incubated for 77 d. In a percolation test, the microcosms were washed with ultra pure water to simulate heavy rain so as to rinse water‐soluble lead (Pbw) from the topsoil layer. Although Pbw remained below detection limits in the mineral soils in all test units, acid‐soluble lead (Pba) increased. Peat amendment diminished Pba in the mineral soil layer, this effect being more pronounced in planted soils, indicating that Pb was taken up by the plants. The percolation test showed that the effect of Scots pine seedlings on Pb movement was minor when peat was added. A long‐term dissolution test revealed that considerably more Pb was released from old pellets into soil extracts than from new ones, whereas only traces of Pb, if any, were dissolved in sterilized pure water.
An Air–Water Interfacial Area Based Variable Tortuosity Model for Unsaturated Sands
Authors: Khaleel Raziuddin , Saripalli K. Prasad
Published: May 2006

A new variable tortuosity definition is introduced that is based on the immiscible fluid (air–water) interfacial area. Unsaturated media tortuosity (τa) is defined as the ratio of aaw to aaw,o where aaw is the estimated air–water interfacial area in a real unsaturated medium (i.e., a soil sample), and aaw,o is the same variable for the corresponding, idealized capillary bundle. The air–water interfacial area for both real and idealized media is directly proportional to the area under their respective retention curves. With τ being the saturated tortuosity, we relate the variable tortuosity ratio (τ/τa) to the Seε term in Mualem's (ε = 0.5) and Burdine's (ε = 2) pore‐size distribution models. Thus, instead of using tortuosity and pore connectivity formulations, which have empirical exponents of either 0.5 or 2, the new model depends on a variable interfacial area for varying saturation and soil texture, as reflected in the measured retention data. We tested the new definition of tortuosity to predict unsaturated hydraulic conductivity, K, as a function of volumetric moisture content, θ, for 22 repacked Hanford sediments that are comprised of mostly coarse and fine sands but some also contain a sizeable fraction (as high as 27%) of fines (silt and clay). Replacing the Seε term in van Genuchten–Mualem (VGM) model by the tortuosity ratio τ/τa, and still using saturated hydraulic conductivity and moisture retention parameters as used in the conventional approach, we obtained τa‐based K(θ) predictions that are nearly identical to the conventional VGM model predictions. We also compared the τa‐based K(θ) predictions with the standard Brooks–Corey–Burdine (BCB) model predictions. In comparison to the VGM model predictions, τa‐based BCB K(θ) predictions appear to be less biased relative to the measured K for the coarse‐textured samples.
Evaluation of Dual‐Permeability Models for Chemical Leaching Assessment to Assist Pesticide Regulation in Hawaii
Authors: Alavi G. , Dusek J. , Vogel T. , Green R. E. , Ray C.
Published: May 2006

Groundwater is the primary source of drinking water for all the islands of Hawaii. Past agricultural practices have led to the contamination of groundwater in certain locations. As a result, the state of Hawaii emphasizes the prevention of contamination of groundwater from the leaching of pesticides. Hawaii currently uses a simple (Tier I) screening assessment model to evaluate the leaching potential of pesticides. This model is only capable of indicating if a chemical is likely to leach; it can estimate neither the concentration profile in soil nor the concentration in leachate water. The USEPA is seeking partnership with the state of Hawaii for examining the feasibility of using Tier II models in Hawaii conditions for pesticide registration. Two pesticide leaching models, MACRO 4.3 and S1D DUAL, were tested using leaching data for five pesticides from a field site on the island of Oahu. Despite deficiencies, it is one of the best data sets currently available for tropical soils. Both MACRO 4.3 and S1D DUAL models explicitly include preferential flow components but use different concepts in model formulations. The performances of the two models were generally similar. The results show that preferential flow had a minor role in transporting the chemicals compared with micropore flow because of the high saturated conductivity of micropores (matrix). We conclude that a process‐based model will contribute substantially to the evaluation of chemical leaching risk and complement the Tier I model that currently is used for pesticide registration in Hawaii.
CART Regulates Islet Hormone Secretion and Is Expressed in the β-Cells of Type 2 Diabetic Rats
Authors: Wierup Nils , Björkqvist Maria , Kuhar Michael J. , Mulder Hindrik , Sundler Frank
Published: June 2006

Cocaine- and amphetamine-regulated transcript (CART) is an anorexigenic peptide widely expressed in the central, peripheral, and enteric nervous systems. CART is also expressed in endocrine cells, including β-cells during rat development and δ-cells of adult rats. We examined the effect of CART 55–102 on islet hormone secretion, using INS-1(832/13) cells and isolated rat islets. In addition, islet CART expression was examined in two rat models of type 2 diabetes: Goto-Kakizaki (GK) rats and dexamethasone (DEX)-treated rats. At high glucose, CART potentiated cAMP-enhanced insulin secretion via the cAMP/protein kinase A-dependent pathway. In the absence of cAMP-elevating agents, CART was without effect on INS-1 cells but modestly inhibited secretion of insulin, glucagon, and somatostatin from isolated islets. CART was markedly upregulated in the β-cells of both diabetes models. Thus, in DEX-treated rats, islet CART mRNA expression, and the number of CART-immunoreactive β-cells were 10-fold higher than in control rats. In GK rats, the relative number of CART-expressing β-cells was 30-fold higher than in control rats. We conclude that CART is a regulator of islet hormone secretion and that CART is upregulated in the β-cells of type 2 diabetic rats.
Adipose Overexpression of Phosphoenolpyruvate Carboxykinase Leads to High Susceptibility to Diet-Induced Insulin Resistance and Obesity
Authors: Franckhauser Sylvie , Muñoz Sergio , Elias Ivet , Ferre Tura , Bosch Fatima
Published: June 2006

Obesity and insulin resistance are associated with increased serum free fatty acids (FFAs). Thus, a reduction in circulating FFAs may increase insulin sensitivity. This could be achieved by increasing FFA reesterification in adipose tissue. Transgenic mice with increased adipose tissue glyceroneogenesis, caused by overexpression of phosphoenolpyruvate carboxykinase (PEPCK), show increased FFA reesterification and develop obesity but are insulin sensitive. Here, we examined whether these transgenic mice were protected from diet-induced insulin resistance. Surprisingly, when fed a high-fat diet for a short period (6 weeks), transgenic mice developed severe obesity and were more hyperinsulinemic, glucose intolerant, and insulin resistant than controls. The high triglyceride accumulation prevented white adipose tissue from buffering the flux of lipids in circulation and led to increased serum triglyceride levels and fat deposition in liver. Furthermore, circulating leptin and FFA concentrations increased to similar levels in transgenic and control mice, while adiponectin levels decreased in transgenic mice compared with controls. In addition, transgenic mice showed fat accumulation in brown adipose tissue, which decreased uncoupling protein-1 expression, suggesting that these mice had impaired diet-induced thermogenesis. These results indicate that increased PEPCK expression in the presence of high-fat feeding may have deleterious effects and lead to severe insulin resistance and type 2 diabetes.
Effects of Type 1 Diabetes on Gray Matter Density as Measured by Voxel-Based Morphometry
Authors: Musen Gail , Lyoo In Kyoon , Sparks Caitlin R. , Weinger Katie , Hwang Jaeuk , Ryan Christopher M. , Jimerson David C. , Hennen John , Renshaw Perry F. , Jacobson Alan M.
Published: June 2006

The effects of type 1 diabetes and key metabolic variables on brain structure are not well understood. Sensitive methods of assessing brain structure, such as voxel-based morphometry (VBM), have not previously been used to investigate central nervous system changes in a diabetic population. Using VBM, we compared type 1 diabetic patients aged 25–40 years with disease duration of 15–25 years and minimal diabetes complications with an age-matched, nondiabetic control group. We investigated whether lower than expected gray matter densities were present, and if so, whether they were associated with glycemic control and history of severe hypoglycemic events. In comparison with control subjects, diabetic patients showed lower density of gray matter in several brain regions. Moreover, in the patient group, higher HbA1c levels and severe hypoglycemic events were associated with lower density of gray matter in brain regions responsible for language processing and memory. Our study represents the first comprehensive study of gray matter density changes in type 1 diabetes and suggests that persistent hyperglycemia and acute severe hypoglycemia have an impact on brain structure.
Cholinergic Involvement in Vascular and Glucoregulatory Actions of Insulin in Rats
Authors: Lévesque Martin , Santuré Marta , Pitre Maryse , Nadeau André , Bachelard Hélène
Published: June 2006

This study was designed to test the glucose metabolic and vasodilator actions of insulin in rats and its relation to cholinergic system–dependent mechanisms. The first group of rats had pulsed Doppler flow probes and intravascular catheters implanted to determine blood pressure, heart rate, and regional blood flows. Insulin sensitivity was assessed by the euglycemic-hyperinsulinemic clamp technique carried out in the absence or presence of atropine. The second group of rats was used to determine the cholinergic contribution to in vivo insulin-mediated glucose utilization in individual muscles. Glucose uptake was examined by using [3H]2-deoxy-d-glucose. Muscarinic cholinergic blockade was found to significantly (P = 0.002) reduce insulin sensitivity and to completely abrogate the renal (P = 0.008) and hindquarter (P = 0.02) vasodilator responses to euglycemic infusion of insulin. A significant reduction in insulin-stimulated in vivo glucose uptake was also noted in soleus (P = 0.006), quadriceps (P = 0.03), gastrocnemius (P = 0.02), and extensor digitorum longus (EDL) (P = 0.001) muscles, when insulin was infused at a rate of 4 mU · kg−1 · min−1, whereas at the rate of 16 mU · kg−1 · min−1, a significant reduction in glucose uptake was only observed in EDL (P = 0.03) and quadriceps (P = 0.01) muscles. Together, these results demonstrate a potential role for cholinergic involvement with physiological insulin actions in glucose clearance and blood flow regulation in rats.
A Severe Diabetic Nephropathy Model With Early Development of Nodule-Like Lesions Induced by Megsin Overexpression in RAGE/iNOS Transgenic Mice
Authors: Inagi Reiko , Yamamoto Yasuhiko , Nangaku Masaomi , Usuda Nobuteru , Okamato Hiroshi , Kurokawa Kiyoshi , van Ypersele de Strihou Charles , Yamamoto Hiroshi , Miyata Toshio
Published: June 2006

Many factors are involved in the pathogenesis of diabetic nephropathy. A single gene abnormality may be prerequisite but insufficient to the disease to manifest. It is therefore only when a second or sometimes a third damage is associated that the consequences of pathogenic phenotypes become evident. We generated the triple transgenic mice overexpressing megsin (a novel glomerular-specific serpin), a receptor for advanced glycation end products (RAGE), and inducible nitric oxide synthase (iNOS). Compared with the single- or two-gene transgenic mice, the triple transgenic mice developed, at an early age (16 weeks), severe albuminuria and renal damage with all of the characteristics of human diabetic nephropathy (i.e., glomerular hypertrophy, diffuse mesangial expansion, inflammatory cell infiltration, and interstitial fibrosis). Interestingly, 30–40% of glomeruli exhibit nodule-like lesions. Oxidative and carbonyl stress makers (pentosidine, Nε-carboxymethyllysine, and 8-hydroxy-deoxyguanosine) were significantly higher in the triple transgenic mice. The iNOS transgenic mice have a diabetes phenotype, the renal consequences of which are moot, and the superimposition of RAGE leads to more conspicuous manifestations. By additional overexpression of megsin, a gene known to be involved in mesangial proliferation and expansion, these local consequences become dramatically manifest and approximate those observed in human pathology. This multiple hit approach is of interest in consideration of the sequential events during development of diabetic nephropathy.
Quantitative Trait Loci on Chromosome 8q24 for Pancreatic β-Cell Function and 7q11 for Insulin Sensitivity in Obese Nondiabetic White and Black Families
Authors: An Ping , Freedman Barry I. , Rich Stephen S. , Mandel Stephen A. , Arnett Donna K. , Myers Richard H. , Chen Yii-Der I. , Hunt Steven C. , Rao D.C.
Published: June 2006

Genome-wide linkage scans were carried out using a multipoint variance components method in white and black families of the NHLBI Hypertension Genetic Epidemiology Network (HyperGEN) study to identify quantitative trait loci (QTLs) for pancreatic β-cell function and insulin sensitivity estimated through the newly released nonlinear computer version of homeostasis model assessment 2. Participants fasting <8 h, with diagnosed type 2 diabetes, or taking blood glucose or blood lipid–lowering medications were excluded. Both phenotypes were adjusted separately by race and sex for the effects of age, BMI, and field center before linkage scans using 370 microsatellite markers were performed. A total of 685 white families (1,180 sibpairs) and 773 black families (775 sibpairs) were evaluated as well as subsets including 267 obese white families (757 sibpairs) and 427 obese black families (599 sibpairs) identified through tree-linkage analyses using interacting covariates of age, sex, and BMI. For β-cell function in the obese white families, significant (logarithm of odds [LOD] score >3.6) evidence supporting linkages was detected on chromosome 8q24 at D8S1179 (135 cM, LOD score 4.2, empirical P = 0.002) and at D8S1128 (140 cM, LOD score 3.7, empirical P = 0.003). In addition, two regions supported linkage for insulin sensitivity index in the obese black families on chromosome 7q11 at D7S3046 (79 cM, LOD score 3.0, empirical P = 0.018) and on chromosome 6q26 at D6S1277 (173 cM, LOD score 3.0, empirical P = 0.018). Reducing clinical heterogeneity using obesity data and improved estimates of β-cell function and insulin sensitivity may have permitted identification of a QTL on chromosome 8q24 for β-cell function in the presence of estimated insulin resistance and a QTL on chromosome 7q11 for insulin sensitivity. These regions replicate previous reports for type 2 diabetes–associated traits.
ACDC/Adiponectin Polymorphisms Are Associated With Severe Childhood and Adult Obesity
Authors: Bouatia-Naji Nabila , Meyre David , Lobbens Stéphane , Séron Karin , Fumeron Frédéric , Balkau Beverley , Heude Barbara , Jouret Béatrice , Scherer Philipp E. , Dina Christian , Weill Jacques , Froguel Philippe
Published: June 2006

Common single nucleotide polymorphisms (SNPs) in the ACDC adiponectin encoding gene have been associated with insulin resistance and type 2 diabetes in several populations. Here, we investigate the role of SNPs −11,377C>G, −11,391G>A, +45T>G, and +276G>T in 2,579 French Caucasians (1,229 morbidly obese and 1,350 control subjects). We found an association between severe forms of obesity and −11,377C (odds ratio 1.23, P = 0.001) and +276T (1.19, P = 0.006). Surprisingly, alternative alleles −11,377G and +276G have been previously reported as risk factors for type 2 diabetes. Transmission disequilibrium tests showed a trend in overtransmission (56.7%) of a risk haplotype 1(C)-1(G)-1(T)-2(T) including −11,377C and +276T in 634 obesity trios (P = 0.097). Family-based analysis in 400 trios from the general population indicated association between obesity haplotype and higher adiponectin levels, suggesting a role of hyperadiponectinemia in weight gain. However, experiments studying the putative roles of SNPs −11,377C>G and +276G>T on ACDC functionality were not conclusive. In contrast, promoter SNP −11,391G>A was associated with higher adiponectin levels in obese children (P = 0.005) and in children from the general population (0.00007). In vitro transcriptional assays showed that −11,391A may increase ACDC activity. In summary, our study suggests that variations at the ACDC/adiponectin gene are associated with risk of severe forms of obesity. However, the mechanisms underlying these possible associations are not fully understood.
Contrasting Insulin Sensitivity of Endogenous Glucose Production Rate in Subjects With Hepatocyte Nuclear Factor-1β and -1α Mutations
Authors: Brackenridge Anna , Pearson Ewan R. , Shojaee-Moradie Fariba , Hattersley Andrew T. , Russell-Jones David , Umpleby A. Margot
Published: June 2006

Heterozygous mutations in the transcription factors hepatocyte nuclear factor (HNF)-1α and -1β result in MODY (maturity-onset diabetes of the young). Despite structural similarity between HNF-1α and -1β, HNF-1β mutation carriers have hyperinsulinemia, whereas HNF-1α mutation carriers have normal or reduced insulin concentrations. We examined whether HNF-1β mutation carriers are insulin resistant. The endogenous glucose production rate and rate of glucose uptake were measured with a two-step, low-dose (0.3 mU · kg−1 · min−1) and high-dose (1.5 mU · kg−1 · min−1) hyperinsulinemic-euglycemic clamp, with an infusion of [6,6-2H2]glucose, in six subjects with HNF-1α mutations, six subjects with HNF-1β mutations, and six control subjects, matched for age, sex, and BMI. Endogenous glucose production rate was not suppressed by low-dose insulin in HNF-1β subjects but was suppressed by 89% in HNF-1α subjects (P = 0.004) and 80% in control subjects (P < 0.001). Insulin-stimulated glucose uptake and suppression of lipolysis were similar in all groups at low- and high-dose insulin. Subjects with HNF-1β mutations have reduced insulin sensitivity of endogenous glucose production but normal peripheral insulin sensitivity. This is likely to reflect reduced action of HNF-1β in the liver and possibly the kidney. This may be mediated through regulation by HNF-1β of the key gluconeogenic enzymes glucose-6-phosphatase or PEPCK.
Hemostatic Markers of Endothelial Dysfunction and Risk of Incident Type 2 Diabetes
Authors: Meigs James B. , O’Donnell Christopher J. , Tofler Geoffrey H. , Benjamin Emelia J. , Fox Caroline S. , Lipinska Izabela , Nathan David M. , Sullivan Lisa M. , D’Agostino Ralph B. , Wilson Peter W.F.
Published: June 2006

Endothelial dysfunction may precede development of type 2 diabetes. We tested the hypothesis that elevated levels of hemostatic markers of endothelial dysfunction, plasminogen activator inhibitor-1 (PAI-1) antigen, and von Willebrand factor (vWF) antigen predicted incident diabetes independent of other diabetes risk factors. We followed 2,924 Framingham Offspring subjects (54% women, mean age 54 years) without diabetes at baseline (defined by treatment, fasting plasma glucose ≥7 or 2-h postchallenge glucose ≥11.1 mmol/l) over 7 years for new cases of diabetes (treatment or fasting plasma glucose ≥7.0 mmol/l). We used a series of regression models to estimate relative risks for diabetes per interquartile range (IQR) increase in PAI-1 (IQR 16.8 ng/ml) and vWF (IQR 66.8% of control) conditioned on baseline characteristics. Over follow-up, there were 153 new cases of diabetes. Age- and sex-adjusted relative risks of diabetes were 1.55 per IQR for PAI-1 (95% CI 1.41–1.70) and 1.49 for vWF (1.21–1.85). These effects remained after further adjustment for diabetes risk factors (including physical activity; HDL cholesterol, triglyceride, and blood pressure levels; smoking; parental history of diabetes; use of alcohol, nonsteroidal anti-inflammatory drugs, exogenous estrogen, or hypertension therapy; and impaired glucose tolerance), waist circumference, homeostasis model assessment of insulin resistance, and inflammation (assessed by levels of C-reactive protein): the adjusted relative risks were 1.18 per IQR for PAI-1 (1.01–1.37) and 1.39 for vWF (1.09–1.77). We conclude that in this community-based sample, plasma markers of endothelial dysfunction increased risk of incident diabetes independent of other diabetes risk factors including obesity, insulin resistance, and inflammation.
In Vivo and In Vitro Glucose-Induced Biphasic Insulin Secretion in the Mouse
Authors: Henquin Jean-Claude , Nenquin Myriam , Stiernet Patrick , Ahren Bo
Published: June 2006

The mechanisms underlying biphasic insulin secretion have not been completely elucidated. We compared the pattern of plasma insulin changes during hyperglycemic clamps in mice to that of glucose-induced insulin secretion and cytosolic calcium concentration ([Ca2+]c) changes in perifused mouse islets. Anesthetized mice were infused with glucose to clamp blood glucose at 8.5 (baseline), 11.1, 16.7, or 30 mmol/l. A first-phase insulin response consistently peaked at 1 min, and a slowly ascending second phase occurred at 16.7 and 30 mmol/l glucose. Glucose-induced insulin secretion in vivo is thus biphasic, with a similarly increasing second phase in the mouse as in humans. In vitro, square-wave stimulation from a baseline of 3 mmol/l glucose induced similar biphasic insulin secretion and [Ca2+]c increases, with sustained and flat second phases. The glucose dependency (3–30 mmol/l) of both changes was sigmoidal with, however, a shift to the right of the relation for insulin secretion compared with that for [Ca2+]c. The maximum [Ca2+]c increase was achieved by glucose concentrations, causing half-maximum insulin secretion. Because this was true for both phases, we propose that contrary to current concepts, amplifying signals are also implicated in first-phase glucose-induced insulin secretion. To mimic in vivo conditions, islets were stimulated with high glucose after being initially perifused with 8.5 instead of 3.0 mmol/l glucose. First-phase insulin secretion induced by glucose at 11.1, 16.7, and 30 mmol/l was decreased by ∼ 50%, an inhibition that could not be explained by commensurate decreases in [Ca2+]c or in the pool of readily releasable granules. Also unexpected was the gradually ascending pattern of the second phase, now similar to that in vivo. These observations indicated that variations in prestimulatory glucose can secondarily affect the magnitude and pattern of subsequent glucose-induced insulin secretion.
Diabetes Enhances mRNA Levels of Proapoptotic Genes and Caspase Activity, Which Contribute to Impaired Healing
Authors: Al-Mashat Hesham A. , Kandru Suneel , Liu Rongkun , Behl Yugal , Desta Tesfahun , Graves Dana T.
Published: June 2006

We previously reported that after a bacteria-induced wound in the scalp, type 2 diabetic (db/db) mice had higher levels of apoptosis of fibroblasts and bone-lining cells that are critical for healing compared with normoglycemic controls. To investigate mechanisms by which this might occur, RNA profiling and caspase activity was measured after inoculation of Porphyromonas gingivalis. Diabetes caused a more than twofold induction of 71 genes that directly or indirectly regulate apoptosis and significantly enhanced caspase-8, -9, and -3 activity. The functional significance of diabetes-induced apoptosis was studied by treating diabetic mice with a pancaspase inhibitor, z-VAD-fmk (N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone). Inhibiting apoptosis significantly improved several parameters of healing, including fibroblast density, enhanced mRNA levels of collagen I and III, and increased matrix formation. Improvements were also noted in bone, with an increase in the number of bone-lining cells and new bone formation. Thus, diabetes-enhanced apoptosis represents an important mechanism through which healing is impaired, and this can be explained, in part, by diabetes-increased expression of proapoptotic genes and caspase activity.
Failure of Transplanted Bone Marrow Cells to Adopt a Pancreatic β-Cell Fate
Authors: Taneera Jalal , Rosengren Anders , Renstrom Erik , Nygren Jens M. , Serup Palle , Rorsman Patrik , Jacobsen Sten Eirik W.
Published: June 2006

Recent studies in normal mice have suggested that transplanted bone marrow cells can transdifferentiate into pancreatic β-cells at relatively high efficiency. Herein, adopting the same and alternative approaches to deliver and fate map-transplanted bone marrow cells in the pancreas of normal as well as diabetic mice, we further investigated the potential of bone marrow transplantation as an alternative approach for β-cell replacement. In contrast to previous studies, transplanted bone marrow cells expressing green fluorescence protein (GFP) under the control of the mouse insulin promoter failed to express GFP in the pancreas of normal as well as diabetic mice. Although bone marrow cells expressing GFP under the ubiquitously expressed β-actin promoter efficiently engrafted the pancreas of normal and hyperglycemic mice, virtually all expressed CD45 and Mac-1/Gr-1, demonstrating that they adopt a hematopoietic rather than β-cell fate, a finding further substantiated by the complete absence of GFP+ cells expressing insulin and the β-cell transcription factors pancreatic duodenal homeobox factor-1 and homeodomain protein. Thus, transplanted bone marrow cells demonstrated little, if any, capacity to adopt a β-cell fate.
Glucokinase Is a Critical Regulator of Ventromedial Hypothalamic Neuronal Glucosensing
Authors: Kang Ling , Dunn-Meynell Ambrose A. , Routh Vanessa H. , Gaspers Larry D. , Nagata Yasufumi , Nishimura Teruyuki , Eiki Junichi , Zhang Bei B. , Levin Barry E.
Published: June 2006

To test the hypothesis that glucokinase is a critical regulator of neuronal glucosensing, glucokinase activity was increased, using a glucokinase activator drug, or decreased, using RNA interference combined with calcium imaging in freshly dissociated ventromedial hypothalamic nucleus (VMN) neurons or primary ventromedial hypothalamus (VMH; VMN plus arcuate nucleus) cultures. To assess the validity of our approach, we first showed that glucose-induced (0.5–2.5 mmol/l) changes in intracellular Ca2+ concentration ([Ca2+]i) oscillations, using fura-2 and changes in membrane potential (using a membrane potential–sensitive dye), were highly correlated in both glucose-excited and -inhibited neurons. Also, glucose-excited neurons increased (half-maximal effective concentration [EC50] = 0.54 mmol/l) and glucose-inhibited neurons decreased (half-maximal inhibitory concentration [IC50] = 1.12 mmol/l) [Ca2+]i oscillations to incremental changes in glucose from 0.3 to 5 mmol/l. In untreated primary VMH neuronal cultures, the expression of glucokinase mRNA and the number of demonstrable glucosensing neurons fell spontaneously by half over 12–96 h without loss of viable neurons. Transfection of neurons with small interfering glucokinase RNA did not affect survival but did reduce glucokinase mRNA by 90% in association with loss of all demonstrable glucose-excited neurons and a 99% reduction in glucose-inhibited neurons. A pharmacological glucokinase activator produced a dose-related increase in [Ca2+]i oscillations in glucose-excited neurons (EC50 = 0.98 mmol/l) and a decrease in glucose-inhibited neurons (IC50 = 0.025 μmol/l) held at 0.5 mmol/l glucose. Together, these data support a critical role for glucokinase in neuronal glucosensing.
Effect of fetal bovine serum and heat-inactivated fetal bovine serum on microbial cell wall-induced expression of procoagulant activity by equine and canine mononuclear cells in vitro
Authors: Okano Shozo , Hurley David J. , Vandenplas Michel L. , Moore James N.
Published: June 2006

Objective—To determine the effect of fetal bovine serum (FBS) and heat-inactivated FBS (HI-FBS) on lipopolysaccharide (LPS)- and zymosan-induced procoagulant activity of equine and canine mononuclear cells.

Sample Population—Mononuclear cells from 18 horses and 3 dogs.

Procedures—Cells were incubated with various concentrations of FBS, HI-FBS, LPS, zymosan, polymyxin B, and anti–LPS-binding protein monoclonal antibody or combinations of these constituents. A 1stage recalcification assay was used to determine procoagulant activity.

Results—Addition of FBS to media significantly increased procoagulant activity; equine and canine cells were stimulated by 1% and 10% FBS, respectively. Coincubation of cells with FBS and polymyxin B did not reduce this effect, suggesting that the response was not attributable to LPS contamination. Addition of HI-FBS to media did not stimulate procoagulant activity of equine or canine cells, and the sensitivity of the equine cells to LPS was significantly increased by HI-FBS. This increased LPS sensitivity was reduced 40% with monoclonal antibody directed against human recombinant LPSbinding protein. Increasing concentrations of HIFBS significantly increased LPS- and zymosaninduced procoagulant activity of canine cells.

Conclusion and Clinical Relevance—Procoagulant activity production in equine and canine mononuclear cells was significantly increased by addition of FBS, whereas heat inactivation of FBS eliminated this effect. Heat inactivation did not eliminate the function of serum proteins involved in enhancement of LPSand zymosan-induced procoagulant activity. Results suggest that HI-FBS can be used as a source of serum proteins that increase the sensitivity of mononuclear cells to bacterial and yeast cell wall components.
Expression of molecular markers in blood of neonatal foals with sepsis
Authors: Pusterla Nicola , Magdesian K. Gary , Mapes Samantha , Leutenegger Christian M.
Published: June 2006

Objective—To determine gene expression of selected molecular markers (tumor necrosis factor [TNF]-α, interleukin [IL]-1β, IL-6, IL-8, IL-10, procalcitonin [PCT], and transforming growth factor [TGF]-β) in the blood of healthy and sick foals.

Animals—28 sick foals without sepsis, 21 foals with sepsis, and 21 healthy foals.

Procedures—Total RNA was extracted from blood samples and converted into complementary DNA (cDNA). Gene expression was measured for the molecular markers by use of real-time PCR assay, and final quantitation was performed with the comparative threshold cycle method.

Results—Samples from all foals yielded transcription for all markers. Expression of TNF-α and TGF-β was significantly lower and that of IL-8 significantly greater in the sick-nonseptic and septic groups, compared with the healthy group. No significant difference in expression of IL-1β, IL-6, and PCT was found between the healthy group and the 2 sick groups. Expression of IL-10 was significantly greater in nonsurvivors, compared with survivors.

Conclusions and Clinical Relevance—The cytokine profile in foals with sepsis may suggest an immunosuppressive state. Expression of IL-10 may be a marker for identification of foals with a guarded prognosis.
Phase I and pharmacokinetic evaluation of the combination of orally administered docetaxel and cyclosporin A in tumor-bearing dogs
Authors: McEntee Margaret C. , Rassnick Kenneth M. , Lewis Lionel D. , Zgola Marsha M. , Beaulieu Bernard B. , Balkman Cheryl E. , Page Rodney L.
Published: June 2006

Objective—To determine the maximum tolerated dose and characterize the pharmacokinetic disposition of an orally administered combination of docetaxel and cyclosporin A (CSA) in dogs with tumors.

Animals—16 client-owned dogs with metastatic or advanced-stage refractory tumors.

Procedures—An open-label, dose-escalation, singledose, phase I study of docetaxel administered in combination with a fixed dose of CSA was conducted. Docetaxel (at doses of 1.5, 1.625, or 1.75 mg/kg) and CSA (5 mg/kg) were administered concurrently via gavage twice during a 3-week period. Plasma docetaxel concentrations were quantified by use of high-performance liquid chromatography, and pharmacokinetic disposition was characterized by use of noncompartmental analysis. Dogs' clinical signs and results of hematologic and biochemical analyses were monitored for evidence of toxicosis.

Results—No acute hypersensitivity reactions were observed after oral administration of docetaxel. Disposition of docetaxel was dose independent over the range evaluated, and pharmacokinetic variables were similar to those reported in previous studies involving healthy dogs, with the exception that values for clearance were significantly higher in the dogs reported here. The maximum tolerated dose of docetaxel was 1.625 mg/kg. Gastrointestinal signs of toxicosis were dose limiting.

Conclusions and Clinical Relevance—The absence of myelosuppression suggested that the docetaxelCSA combination may be administered more frequently than the schedule used. Further studies are warranted to evaluate combination treatment administered on a biweekly schedule in dogs with epithelial tumors.
Pharmacokinetics of voriconazole after oral and intravenous administration to horses
Authors: Davis Jennifer L. , Salmon Jacklyn H. , Papich Mark G.
Published: June 2006

Objective—To characterize pharmacokinetics of voriconazole in horses after oral and IV administration and determine the in vitro physicochemical characteristics of the drug that may affect oral absorption and tissue distribution.

Animals—6 adult horses.

Procedures—Horses were administered voriconazole (1 mg/kg, IV, or 4 mg/kg, PO), and plasma concentrations were measured by use of high-performance liquid chromatography. In vitro plasma protein binding and the octanol:water partition coefficient were also assessed.

Results—Voriconazole was adequately absorbed after oral administration in horses, with a systemic bioavailability of 135.75 ± 18.41%. The elimination half-life after a single orally administered dose was 13.11 ± 2.85 hours, and the maximum plasma concentration was 2.43 ± 0.4 μg/mL. Plasma protein binding was 31.68%, and the octanol:water partition coefficient was 64.69. No adverse reactions were detected during the study.

Conclusions and Clinical Relevance—Voriconazole has excellent absorption after oral administration and a long half-life in horses. On the basis of the results of this study, it was concluded that administration of voriconazole at a dosage of 4 mg/kg, PO, every 24 hours will attain plasma concentrations adequate for treatment of horses with fungal infections for which the fungi have a minimum inhibitory concentration ≤ 1 μg/mL. Because of the possible nonlinearity of this drug as well as the potential for accumulation, chronic dosing studies and clinical trials are needed to determine the appropriate dosing regimen for voriconazole in horses.
Use of a simulation model to evaluate sampling strategies for characterization of antimicrobial resistance in non–type-specific Escherichia coli isolated from dairy cows
Authors: Villarroel Aurora , Morley Paul S. , Wittum Thomas E. , Bolte Denise S.
Published: June 2006

Objective—To evaluate various sampling strategies for potential use in measuring prevalence of antimicrobial susceptibility in cattle.

Sample Population—500 isolates of non–type-specific Escherichia coli (NTSEC) isolated from the feces of 50 cows from 2 dairy farms (25 cows/farm and 10 isolates/cow).

Procedures—Diameters of inhibition zones for 12 antimicrobials were analyzed to estimate variation among isolates, cows, and farms and then used to determine sampling distributions for a stochastic simulation model to evaluate 4 sampling strategies. These theoretic sampling strategies used a total of 100 isolates in 4 allocations (1 isolate from 100 cows, 2 isolates from 50 cows, 3 isolates from 33 cows, or 4 isolates from 25 cows).

Results—Analysis of variance composition revealed that 74.2% of variation was attributable to isolates, 18.5% to cows, and 7.3% to farms. Analysis of results of simulations suggested that when most of the variance was attributable to differences among isolates within a cow, culturing 1 isolate from each of 100 cows underestimated overall prevalence, compared with results for culturing more isolates per cow from fewer cows. When variance was not primarily attributable to differences among isolates, all 4 sampling strategies yielded similar results.

Conclusions and Clinical Relevance—It is not always possible to predict the hierarchical level at which clustering will have its greatest impact on observed susceptibility distributions. Results suggested that sampling strategies that use testing of 3 or 4 isolates/cow from a representative sample of all animals better characterize herd prevalence of antimicrobial resistance when impacted by clustering.
Characterization of canine mitochondrial protein expression in natural and induced forms of idiopathic dilated cardiomyopathy
Authors: Lopes Rosana , Solter Philip F. , Sisson D. David , Oyama Mark A. , Prosek Robert
Published: June 2006

Objective—To map canine mitochondrial proteins and identify qualitative and quantitative differences in heart mitochondrial protein expression between healthy dogs and dogs with naturally occurring and induced dilated cardiomyopathy (DCM).

Sample Population—Left ventricle samples were obtained from 7 healthy dogs, 7 Doberman Pinschers with naturally occurring DCM, and 7 dogs with induced DCM.

Procedures—Fresh and frozen mitochondrial fractions were isolated from the left ventricular free wall and analyzed by 2-dimensional electrophoresis. Protein spots that increased or decreased in density by ≥ 2-fold between groups were analyzed by matrixassisted laser desorption/ionization time-of-flight mass spectrometry or quadrupole selecting, quadrupole collision cell, time-of-flight mass spectrometry.

Results—Within narrow pH gradients of control canine heart mitochondrial samples, a total of 1,528 protein spots were revealed. Forty subunits of heart mitochondrial proteins that differ significantly from control tissues were altered in tissue specimens from dogs with naturally occurring and induced forms of DCM. The most affected heart mitochondrial proteins in both groups were those of oxidative phosphorylation (55%). Upregulation of manganese superoxide dismutase was suggestive of heart oxidative injury in tissue specimens from dogs with both forms of DCM. Evidence of apoptosis was associated with overexpression of the heart mitochondrial voltage-dependent anion channel-2 protein and endonuclease G in tissue specimens from dogs with induced DCM.

Conclusions and Clinical Relevance—Alterations of heart mitochondrial proteins related to oxidative phosphorylation dysfunction were more prevalent in tissue specimens from dogs with induced or naturally occurring DCM, compared with those of control dogs.
Comparison of B-mode and Doppler ultrasonographic findings with histologic features of benign and malignant mammary tumors in dogs
Authors: Nyman Helena T. , Nielsen Ole L. , McEvoy Fintan J. , Lee Marcel H. , Martinussen Torben , Hellmén Eva , Kristensen Annemarie T.
Published: June 2006

Objective—To compare and correlate B-mode and color Doppler ultrasonographic characteristics with the histologic findings of benign and malignant mammary tumors in dogs.

Study Population—49 mammary tumors in 26 dogs.

Procedures—Before excision, tumors were evaluated via B-mode and color Doppler ultrasonography to assess size, echogenicity, echopattern, acoustic transmission, invasiveness, and vascularity. Paraffinembedded microsections of the tumors were stained with H&E and examined for presence of necrosis, cysts, cartilage, bone, mineralization, invasion of surrounding tissue, and tissue heterogeneity. To assess vascularity, the number and distribution of vessels that were stained by the Verhoeff van Gieson technique were recorded.

Results—Tumor echogenicity and echopattern on ultrasonographic images correlated with tissue heterogeneity detected histologically. Acoustic enhancement was correlated with the presence of necrotic or cystic areas. Tumor invasion into surrounding tissues as determined ultrasonographically did not correlate with the histologic findings. There was a significant correlation between the number of detected vessels and distribution of flow within the tumors determined via ultrasonographic and histologic examinations.

Conclusions and Clinical Relevance—In canine mammary tumors, ultrasonographic characteristics appear to be correlated with histopathologic changes. Data suggest that ultrasonography may have an important role in the evaluation of mammary tumors in dogs, particularly in the evaluation of tissue composition and tumor vascularity.
Signalment, clinical signs, and prognostic indicators associated with high-grade second- or third-degree atrioventricular block in dogs: 124 cases (January 1, 1997–December 31, 1997)
Authors: Schrope Donald P. , Kelch William J.
Published: June 2006

Objective—To evaluate signalment, clinical signs, and prognosis associated with high-grade second- or thirddegree atrioventricular block (AVB) in dogs.

Design—Retrospective case series.

Animals—124 dogs.

Procedures—Data were gathered from ECGs, veterinarian questionnaires, echocardiograms, and radiographs submitted for review; compared with data from a large control group; and examined for association between variables and duration of survival. A new classification system for AVB was evaluated.

Results—Afghan, Catahoula Leopard Dog, Chow Chow, Cocker Spaniel, German Wirehaired Pointer, and Labrador Retriever breeds were predisposed to highgrade second- or third-degree AVB. Heavier, older, and sexually intact female dogs were overrepresented in the study group. Weakness, lethargy, exercise intolerance, and syncope were the most common clinical signs. The presence of clinical signs was not associated with duration of survival. Dogs with high-grade second-degree AVB had a duration of survival similar to that of dogs with third-degree AVB. Dogs with highgrade second- or third-degree AVB were at high risk for sudden death in the first 6 months after diagnosis. High ventricular escape rhythm rate and narrow escape-complex QRS width were negatively associated with duration of survival. Pacemaker implantation had a significant positive association with survival.

Conclusions and Clinical Relevance—Pacemaker implantation should be strongly considered in all dogs with high-grade second- or third-degree AVB regardless of whether clinical signs are evident. If medical treatment is warranted, vagolytic medications may be the best choice. A new classification system for AVB may merit further investigation.