Structure of the 70S ribosome complexed with mRNA and tRNA   总被引：1，自引：0，他引：1  

Selmer M  Dunham CM  Murphy FV  Weixlbaumer A  Petry S  Kelley AC  Weir JR  Ramakrishnan V 《Science (New York, N.Y.)》2006,313(5795):1935-1942

The crystal structure of the bacterial 70S ribosome refined to 2.8 angstrom resolution reveals atomic details of its interactions with messenger RNA (mRNA) and transfer RNA (tRNA). A metal ion stabilizes a kink in the mRNA that demarcates the boundary between A and P sites, which is potentially important to prevent slippage of mRNA. Metal ions also stabilize the intersubunit interface. The interactions of E-site tRNA with the 50S subunit have both similarities and differences compared to those in the archaeal ribosome. The structure also rationalizes much biochemical and genetic data on translation.  相似文献   

Study of feline injection site sarcomas     

Dean R  Adams V  Whitbread T  Scase T  Dunham S  Mellor D  Philbey A  McCandlish I  Pfeiffer D  Smith K 《The Veterinary record》2006,159(19):641-642

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Clinical features and outcome in dogs and cats with obsessive-compulsive disorder: 126 cases (1989-2000)     

Overall KL  Dunham AE 《Journal of the American Veterinary Medical Association》2002,221(10):1445-1452

OBJECTIVE: To determine clinical features and outcome in dogs and cats with obsessive-compulsive disorder (OCD). DESIGN: Retrospective study. ANIMALS: 103 dogs and 23 cats. PROCEDURES: Records of patients with OCD were analyzed for clinical features, medication used, extent of behavior modification, and outcome. RESULTS: Most dogs affected with OCD had been obtained from breeders. Male dogs significantly outnumbered females (2:1). Female cats outnumbered male cats by 2:1 in a small sample. Most affected dogs lived in households with 2 or more humans and other dogs or cats, and had some formal training. Client compliance with behavior modification was high. A combination of behavior modification and medication resulted in a large decrease in intensity and frequency of OCD in most animals. Clomipramine was significantly more efficacious for treatment in dogs than was amitriptyline. Only 1 dog and 1 cat were euthanatized because of OCD during the study. CONCLUSIONS AND CLINICAL RELEVANCE: OCD in dogs does not appear to be associated with lack of training, lack of household stimulation, or social confinement. In cats, OCD may be associated with environmental and social stress. Obsessive-compulsive disorder appears at the time of social maturity and may have sporadic and heritable forms. With appropriate treatment (consistent behavior modification and treatment with clomipramine), frequency and intensity of clinical signs in most dogs and cats may decrease by > 50%. Success appears to depend on client understanding and compliance and the reasonable expectation that OCD cannot be cured, but can be well controlled.  相似文献   

Electrocardiographic assessment of antianxiety medication in dogs and correlation with serum drug concentration     

Reich MR  Ohad DG  Overall KL  Dunham AE 《Journal of the American Veterinary Medical Association》2000,216(10):1571-1575

OBJECTIVES: To determine effects of tricyclic antidepressants (TCA) on the ECG of dogs treated for behavioral conditions and to examine correlations between ECG findings and serum concentrations of these medications. DESIGN: Repeated-measures study. ANIMALS: 39 client-owned dogs with behavioral problems. PROCEDURE: Two groups of dogs with behavioral problems were evaluated. In group 1 (n = 20), ECG tracings were recorded before starting treatment with TCA and again after treatment for > or = 1 month. Dogs in group 2 were already on long-term maintenance amounts of antianxiety medication when ECG tracings were recorded and serum concentrations of medications were obtained. RESULTS: Significant differences were not detected for dogs in group 1 between ECG values measured before and after TCA administration. The ECG values for dogs in group 2 did not differ significantly from the mean of group-1 dogs before receiving medication or from the reference range used at our facility. Duration of the P wave had a significant positive correlation with serum concentrations of clomipramine but significant negative correlation with serum concentrations of amitriptyline. The QT interval corrected for heart rate had a significant negative correlation with serum concentrations of amitriptyline. CONCLUSIONS AND CLINICAL RELEVANCE: Amitriptyline and clomipramine administered at standard dosages apparently do not cause ECG abnormalities in healthy dogs with behavioral problems. These medications should be used cautiously in dogs with conduction abnormalities, and clinicians should periodically monitor ECG and use good clinical judgment to weigh risks and benefits of medications for the safety of each dog.  相似文献   

DRAFTS AND COLDS     

Dunham HF 《Science (New York, N.Y.)》1911,34(877):514

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Combination of total solids determined by oven drying and fat determined by Mojonnier extraction for measurement of solids-not-fat content of raw milk: collaborative study     

J L Clark  D M Barbano  C E Dunham 《Journal of the Association of Official Analytical Chemists》1989,72(5):719-724

Each of 9 laboratories analyzed 9 pairs of blind duplicate raw milk samples for fat, using the Mojonnier ether extraction method (16.E13-16.E17), and for total solids, using a new direct forced air oven method. Solids-not-fat was determined by subtracting percent fat from percent total solids. The solids-not-fat content of the samples tested in the collaborative study ranged from 8.48 to 9.36%. The average repeatability standard deviation (sr) and the average reproducibility standard deviation (SR) for the solids-not-fat method were 0.019 and 0.041, respectively. Average repeatability (RSDr) and reproducibility (RSDR) relative standard deviations were 0.218 and 0.466%, respectively. The mean repeatability value (r) was 0.055; the mean reproducibility value (R) was 0.117. The difference between milk total solids determined by direct forced air oven drying and milk fat determined by Mojonnier ether extraction has been approved for interim official first action for determination of solids-not-fat content of milk.  相似文献   

Effects of constant and cyclical thermal regimes on growth and feeding of juvenile cutthroat trout of variable sizes   总被引：2，自引：0，他引：2  

M. H. Meeuwig  J. B. Dunham  J. P. Hayes  G. L. Vinyard 《Ecology of Freshwater Fish》2004,13(3):208-216

Abstract –  The effects of constant (12, 18, and 24 °C) and cyclical (daily variation of 15–21 and 12–24 °C) thermal regimes on the growth and feeding of Lahontan cutthroat trout ( Oncorhynchus clarki henshawi ) of variable sizes were examined. Higher constant temperatures (i.e., 24 °C) and more variable daily temperatures (i.e., 12–24 °C daily cycle) negatively affected growth rates. As fish mass increased (from 0.24 to 15.52 g) the effects of different thermal regimes on mass growth became more pronounced. Following 14 days exposure to the thermal regimes, feeding rates of individual fish were assessed during acute exposure (40 min) to test temperatures of 12, 18, and 24 °C. Feeding rate was depressed during acute exposure to 24 °C, but was not significantly affected by the preceding thermal regime. Our results indicate that even brief daily exposure to higher temperatures (e.g., 24 °C) can have considerable sublethal effects on cutthroat trout, and that fish size should be considered when examining the effects of temperature.  相似文献   

Toxicologic studies with lambs fed sugar beets grown on municipal sludge-amended soil: lowered relative hemoglobin in red blood cells and mutagens in blood and excreta     

J N Telford  J G Babish  P B Dunham  D E Hogue  K W Miller  G S Stoewsand  B H Magee  J R Stouffer  C A Bache  D J Lisk 《American journal of veterinary research》1984,45(12):2490-2494

Sugar beets grown on municipal sludge-amended soil were fed to growing lambs for 66 days. The relative hemoglobin content was significantly lower (P less than 0.05) in the lambs fed the sludge-grown sugar beets. The concentration of direct-acting mutagens was significantly higher (P less than 0.05) than controls in blood and urine of the lambs fed the sludge-grown beets. Cadmium concentration was higher, but not significantly (P greater than 0.05) in the livers and kidneys of the lambs fed the sludge-grown beets as compared with controls. Significant differences between treatment groups were not observed in active or passive K+ influxes in RBC; in the activity of hepatic microsomal aniline hydroxylase in p-nitroanisole-O-demethylase, aminopyrene-N-demethylase, or arylhydrocarbon hydroxylase; in tissue ultrastructure of kidney, liver, or muscle as examined by electron microscopy; or in carcass weight, dressing percentage, quality, or yield grade.  相似文献   

The surface of Mars: the view from the viking 2 lander     

Mutch TA  Grenander SU  Jones KL  Patterson W  Arvidson RE  Guinness EA  Avrin P  Carlston CE  Binder AB  Sagan C  Dunham EW  Fox PL  Pieri DC  Huck FO  Rowland CW  Taylor GR  Wall SD  Kahn R  Levinthal EC  Liebes S  Tucker RB  Morris EC  Pollack JB  Saunders RS  Wolf MR 《Science (New York, N.Y.)》1976,194(4271):1277-1283

Viking 2 lander began imaging the surface of Mars at Utopia Planitia on 3 September 1976. The surface is a boulder-strewn reddish desert cut by troughs that probably form a polygonal network. A plateau can be seen to the east of the spacecraft, which for the most probable lander location is approximately the direction of a tongue of ejecta from the crater Mie. Boulders at the lander 2 site are generally more vesicular than those near lander i. Fines at both lander sites appear to be very fine-grained and to be bound in a duricrust. The pinkish color of the sky, similar to that observed at the lander I site, indicates suspension of surface material. However, the atmospheric optical depth is less than that at the lander I site. After dissipation of a cloud of dust stirred during landing, no changes other than those stemming from sampling activities have been detected in the landscape. No signs of large organisms are apparent at either landing site.  相似文献   

Estimating the mass of asteroid 253 mathilde from tracking data during the NEAR flyby   总被引：1，自引：0，他引：1  

DK Yeomans  J Barriot  DW Dunham  RW Farquhar  JD Giorgini  CE Helfrich  AS Konopliv  JV McAdams  JK Miller  WM Owen  DJ Scheeres  SP Synnott  BG Williams 《Science (New York, N.Y.)》1997,278(5346):2106-2109

The terminal navigation of the Near Earth Asteroid Rendezvous (NEAR) spacecraft during its close flyby of asteroid 253 Mathilde involved coordinated efforts to determine the heliocentric orbits of the spacecraft and Mathilde and then to determine the relative trajectory of the spacecraft with respect to Mathilde. The gravitational perturbation of Mathilde on the passing spacecraft was apparent in the spacecraft tracking data. As a result of the accurate targeting achieved, these data could be used to determine Mathilde's mass as 1.033 (+/- 0.044) x 10(20) grams. Coupled with a volume estimate provided by the NEAR imaging team, this mass suggests a low bulk density for Mathilde of 1.3 grams per cubic centimeter.  相似文献