Interaction of flavonoids with bovine serum albumin: a fluorescence quenching study   总被引：6，自引：0，他引：6  

Papadopoulou A  Green RJ  Frazier RA 《Journal of agricultural and food chemistry》2005,53(1):158-163

The interaction between four flavonoids (catechin, epicatechin, rutin, and quercetin) and bovine serum albumin (BSA) was investigated using tryptophan fluorescence quenching. Quenching constants were determined using the Stern-Volmer equation to provide a measure of the binding affinity between the flavonoids and BSA. The binding affinity was strongest for quercetin and ranked in the order quercetin > rutin > epicatechin = catechin. The pH in the range of 5-7.4 does not affect significantly (p < 0.05) the association of rutin, epicatechin, and catechin with BSA, but quercetin exhibited a stronger affinity at pH 7.4 than at lower pH (p < 0.05). Quercetin has a total quenching effect on BSA tryptophan fluorescence at a molar ratio of 10:1 and rutin at approximately 25:1. However, epicatechin and catechin did not fully quench tryptophan fluorescence over the concentration range studied. Furthermore, the data suggested that the association between flavonoids and BSA did not change molecular conformation of BSA and that hydrogen bonding, ionic, and hydrophobic interaction are equally important driving forces for protein-flavonoid association.  相似文献   

Concentrations of trimethoprim and sulfamethoxazole in cerebrospinal fluid and serum in mares with and without a dimethyl sulfoxide pretreatment.          下载免费PDF全文

S L Green  I G Mayhew  M P Brown  R R Gronwall    G Montieth 《Canadian journal of veterinary research》1990,54(2):215-222

Each of seven mares was given an intravenous (IV) injection of 40% dimethyl sulfoxide (DMSO) at a dosage of 1 g/kg, over 35 min, immediately followed by a single IV injection of a trimethoprim (TMP) and sulfamethoxazole (SMZ) combination (SMZ 83%, TMP 17%) at a combined dosage of 44 mg/kg (7.48 mg/kg TMP; 36.52 mg/kg SMZ). Each horse served as its own control and was alternately treated with an identical dose of TMP-SMZ treatment alone at least seven days following or preceding the DMSO and TMP-SMZ treatment. Serum and cerebrospinal fluid (CSF) concentrations of TMP and SMZ were measured over a six hour period. Dimethyl sulfoxide treatment caused no significant difference in the mean serum concentration of SMZ or in the mean CSF concentrations of TMP or SMZ. The mean serum concentration of TMP was significantly (p less than 0.05) increased at the two, four and six hour sampling time in the mares receiving pretreatment with DMSO. The clearance of TMP was also significantly (p less than 0.05) decreased from 675 mL/h/kg to 327 mL/h/kg by DMSO administration. Concentrations of TMP and SMZ in the CSF in both treatment groups exceeded the minimum inhibitory concentrations for many common bacterial pathogens of equine origin. In addition, CSF concentration of TMP exceeded the serum concentrations required for 50% inhibition of dihydrofolate reductases of protozoan origin. Serum TMP and SMZ concentration were similar to those reported to be effective against Toxoplasma gondii in in vitro studies on the killing or inhibition of the organism.  相似文献   

Eel acetylcholinesterase inhibition studies with heteroarylphosphinates     

Claire N. Lieske  James H. Clark  Howard G. Meyer  Leigh Boldt  Martin D. Green  John R. Lowe  Walter E. Sultan  Peter Blumbergs  Matthew A. Priest 《Pesticide biochemistry and physiology》1984,22(3):285-294

The inhibition of eel acetylcholinesterase by the 4-nitrophenyl esters of 2-furyl(methyl)-, methyl(2-thienyl)-, di-2-furyl-, and di-2-thienylphosphinic acid (I, II, III, and IV, respectively) was investigated at pH 6.90 in 0.067 M phosphate buffer (25.0°C) using stopped-flow instrumentation and automated data processing. Our evaluation of the dissociation constant, K_d, the unimolecular bonding rate constant, k₂, and the bimolecular reaction constant, k_i, are the first reported values for these constants for alkyl/heteroaryl and diheteroaryl esters of phosphinic acids. The largest k_i value (19,330 M^?1 sec^?1) was observed for the reaction of I with the enzyme. The order for the remaining three is II > IV > III. There is no direct relationship between the hydrolysis rates of the esters and their anticholinesterase activities on eel acetylcholinesterase. Likewise, there is no direct relationship between their anticholinesterase activities and the LD₅₀ values in rats.  相似文献   

Letter: Elaphostrongylus cervi in red deer.     

P C Mason  N R Kiddey  R J Sutherland  D M Rutherford  A G Green 《New Zealand veterinary journal》1976,24(1-2):22-23

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Avian reoviruses in New Zealand.     

A F Green  J K Clarke  J E Lohr 《New Zealand veterinary journal》1976,24(8):181-183

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Acid-base status and electrolyte alterations associated with diarrhea in non-suckling horses     

E.A. Wilson DVM  MS  R.A. Green DVM  PhD   《Journal of Equine Veterinary Science》1986,6(6):321-325

A retrospective search of medical records of 56 adult horses with diarrhea of variable duration disclosed a variety of blood gas and electrolyte abnormalities at the time of admission. The acid-base and electrolyte disturbances were analyzed and classified according to the duration of diarrhea. In horses with acute diarrhea (duration <6 days) the most common disorder was combined anion gap metabolic acidosis and metabolic alkalosis (72%)characterized by significant hyponatremia, hypochloridemia, and hyperkalemia. The most severe acidemia was found in horses with diarrheas of intermediate duration (1–2 weeks). In this group hyperchloremic metabolic acidosis was commonly found (43%). In horses with diarrhea of long duration (>4 weeks) blood gas and electrolyte values were usually within normal limits. Although the above findings suggest differing therapeutic approaches might be based on the duration of the diarrhea, many cases differed markedly from the mean with respect to their underlying disturbances and, therefore, optimal fluid therapy should be based on the patient's blood gas and electrolyte status.  相似文献   

Correlations of stomatal conductance with hydraulic, chemical and environmental variables in five urban tree species     

T. Brendon Johnson  Robert M. Aug  Craig D. Green  Ann J. W. Stodola  Joshua B. Olinick  Arnold M. Saxton 《Scientia Horticulturae》2001,90(3-4):305-320

Recent findings suggest that stomatal conductance (g_s) may be as closely linked to plant chemical variables as to hydraulic variables. To test this in an urban field setting, we examined seasonal g_s in relation to a number of plant and environmental variables in five temperate, deciduous tree species. Stomatal conductance was generally more closely correlated with abscisic acid concentrations in xylem sap than with shoot water potential, shoot osmotic potential, pH of xylem sap or environmental variables. Seasonal g_s was mostly poorly correlated with shoot water potential and osmotic potential. Among environmental variables, PPFD accounted for most variability in g_s. We tested a model, developed previously in maize, that describes regulation of g_s by abscisic acid concentration of xylem sap with leaf water status acting to modify stomatal sensitivity to the abscisic acid signal. This model explained somewhat more variation in g_s than abscisic acid concentrations alone. Response surface models, especially those incorporating environmental variables, were most successful at explaining g_s. Our findings with urban trees are consistent with the theory of regulation of g_s by root-sourced abscisic acid.  相似文献   

Effects of dietary rhIGF-I in neonatal calves on the appearance of glucose, insulin, D-xylose, globulins and γ-glutamyl transferase in blood     

C. R. Baumrucker  M. H. Green  J. W. Blum 《Domestic animal endocrinology》1994,11(4):393-403

Cow colostrum is rich in insulin-like growth factors IGF-I and II, thus the dietary effects of recombinant human (rh) rhIGF-I on the newborn were of interest. The objective of this study was to examine the effects of dietary IGF-I upon selected blood components and gut absorptive development. Calves were blocked by birth weight and fed two times per d for a total of four times with the initial restricted diet. The initial feeding was 1.5 l and the remaining three feedings were at 2 1 with one of three experimental diets: 1) milk replacer plus isolated colostrum derived globulins (MR⁻), 2) same as 1 above plus 750 ng/ml rhIGF-I (MR⁺), 3) pooled cow colostrum (COL). Thereafter, all animals received only milk replacer at 5% of body weight (BW)/feeding two times per d with only treatment 2 having continued addition of 750 ng/ml rhIGF-I until experimental completion at 6 to 7 d after birth. At feeding three, animals were fed D-xylose (0.5 g/kg BW) and 5,000 U of bovine kidney membrane γ-glutamyl transferase as indicators of gut absorptive capacity. Colostrum-fed animals received 5,000 U of natural occurring γ-glutamyl transferase activity in the 1.5 l first feeding. Blood samples taken over time were collected and saved as frozen plasma. All diets were analyzed for nutrient composition and endogenous levels of test hormones. Colostrum fed calves had greater globulin concentration (P < 0.01) than MR⁻ or MR⁺ fed calves. Recombinant hIGF-I feeding had no effect (MR⁻ vs. MR⁺) upon total protein, albumin or globulin blood levels. Absorption of colostrum γ-glutamyl transferase at first feeding resulted in a peak total blood U of 4.5% of that fed. Although enzyme absorption was greatly reduced by the third feeding (0.5% of total fed), MR⁺ fed calves exhibited no significant difference in enzyme absorption when compared with the controls (MR⁻ vs. MR⁺). However, pharmacokinetic analysis of D-xylose absorption at the third feeding showed diet effect upon absorption of D-xylose. Dietary rhIGF-I may change development or activity of sugar transporters and also may alter absorption of macromolecules (closure) in neonatal calves.  相似文献   

Lamb morbidity in three housed flocks in south-west England during two lambing seasons—farmer versus veterinary monitoring     

L. E. Green  E. Berriatua  K. L. Morgan 《Preventive veterinary medicine》1994,19(3-4):233-240

A 2 year investigation into diseases of early-born, housed lambs was carried out from 1989 to 1991. The mortality, morbidity and sub-clinical disease of housed lambs from three flocks were studied. This paper describes the collection and analysis of morbidity data.

Morbidity was assessed using two techniques. In the first year, a cohort of approximately 80 lambs per flock was observed at regular (7 or 14 day) intervals from birth to slaughter at 10–26 weeks of age. Each lamb was examined using a routine clinical examination carried out by two out of three members of a trained team of veterinarians.

The technique used was thought to be objective and accurate. However, because there was a small proportion (10–12%) of lambs examined there was a lack of information on severely sick lambs and only diseases of prevalence greater than 3.5% had a 95% probability of being identified. This led to a change im the method of data collection in the second year when the whole flock of lambs was observed by farmers and lambs which they considered sick were presented for treatment.

Seventeen clinical entities were detected in the first year; these were primarily mild conditions. In lambs from Cohorts A, B and C, the mortality rates were 11.8%, 10.5% and 1.3%, respectively. In the second year, 16 diseases were observed. Lambs presented by the farmers were overtly sick; 15.3% from Flock A and 29.2% from Flock B died. There were no sick lambs presented by Farmer C. In the second year, sick lambs were observed but the objectivity of the study was considered to have decreased from the first year. Evidence of this came from the inter-observer bias between farmers. There was a significant difference in the proportion of sick lambs presented by Farmers A and B but there was no significant difference in the proportion of lambs which subsequently died (1.6% and 1.8 %) of lambs born in Cohorts A and B, respectively) and which had been presented for treatment, suggesting that Farmer A selected less severely sick lambs than Farmer B.  相似文献   

Vitamin E and selenium responsive myocardial degeneration in dogs.          下载免费PDF全文

P D Green  J W Lemckert 《The Canadian veterinary journal. La revue veterinaire canadienne》1977,18(10):290-291

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