Because of the complexity arising from the large molecular size and the amino acid sequence homologies of IgG-binding domains of Staphylococcal Protein A (SpA), we have introduced a combination of ...stable isotope labeling and both qualitative and quantitative investigations of the structural dependence of the NMR chemical shifts for its structure analysis. In order to enable selective isotope labeling with high efficiency, a mutated low molecular weight Protein A (LPA; MWt=27 kDa) which consists of E, D, A, B and 13 residues of the C-domain was used in this study. Amide proton chemical shifts, measured using uniformly
15N-labeled LPA and LPA labeled selectively with
15N-alanine, show that the turn between helices 1 and 2, and its tertiary interactions with helix 3, are very similar in all domains. This contradicts previous results obtained using independent structure calculations on isolated domains. The close similarity in NH and
15N chemical shifts of alanine residues in the interdomain linker suggests that the linker maintains a similar structure both in isolated domains and in the intact protein. We show that the high-field shifted methyl signal of Ala 48 is affected by the ring-current effect arising from Phe 30, and has a very similar helical environment in all four domains. Thus, helix 3 is present in all domains, as we previously reported Kikuchi et al., J Biochem Biophys Method, 1999:38:203–208, even though it is not observed in the crystal structure Deisenhofer J. Biochemistry 1981;20:2361–2370.
ABSTRACT
Conjugal transferability of drug resistance was examined, in eleven Pseudomonas aeruginosa strains which were isolated in Frankfurt. Four R factors were demonstrated from three strains using ...P. aeruginosa as recipients but they were nontransferable to Escherichia coli K12. Two R factors, i.e., Rms146 and Rms147, mediated resistances to tetracycline (TC), streptomycin (SM), sulfanilamide (SA), kanamycin (KM), lividomycin (LV), gentamicin C complex (GM) and 3′,4′‐dideoxykanamycin B (DKB). They mediated the formation of aminoglycoside‐inactivating enzymes, i.e., SM phosphotransferase, SM adenylyltransferase, KM and LV phosphotransferase 1, and GM and DKB 6′‐N‐acetyltransferase. TC resistance conferred by these R factors was due to impermeability of the drug. P. aeruginosa Ps 142 carried two kinds of R factor in one cell, Rms148 (SM) and Rms149 (SM·SA·GM·CPC) (CPC, carbenicillin). Rms148 (SM) was transferable at a high frequency of 10–1 and mediated the formation of SM phosphotransferase. Rms149 mediated the formation of drug‐inactivating enzymes, i.e., GM 3‐N‐acetyltransferase and β‐lactamase, but did not inactivate SM. SM resistance was probably due to impermeability of the drug.
Deoxynivalenol (DON), a mycotoxin produced mainly by Fusarium graminearum and F. culmorum commonly contaminates food commodities across the globe. Due to this, exposure to DON might pose potential ...health hazards to humans and animals. Biological factors like sex and age can influence the toxicity of DON. However, in toxicological studies involving DON, the sex and age-dependent response has been often overlooked. Thereby, the objective of this study was to evaluate if sex differences are evident in DON's systemic effects in peripubertal rats. Juvenile animals (n = 24) with 28 days postnatal day were randomly assigned to two experimental groups: Control group (n = 12, 6 females and 6 males, mycotoxin-free diet) and DON group (n = 12, 6 females and 6 males, diet containing 10 mg DON/kg of feed). During 28 days of treatment, the animals were weighed weekly and body weight gain and food intake were calculated for each week. After the experimental period, blood samples, intestine, liver, and kidney were collected and destined for biochemical, hematological, histopathological, and oxidative stress analyses. Greater anorectic responses were seen in males, while only females showed increased levels of creatinine and triglycerides. Regardless of sex, DON induces an increased number of white blood cells, particularly lymphocytes and a significant reduction in the levels of hemoglobin, hematocrit, mean corpuscular hemoglobin, and neutrophils. In males and females fed a DON-contaminated diet, histological lesions were observed in the intestine, liver, and kidney. Ingestion of DON induced a significant increase in the antioxidant potential in the intestine, liver, and kidney. However, this effect was not able to prevent oxidative stress in the renal tissue. Taken together, our results showed a sex-related response in food intake, weight gain, and biochemical parameters in rats exposed to DON during the juvenile and peripubertal periods. In addition, we have verified that oxidative stress is an important mechanism in the nephrotoxicity of DON.
Display omitted
•DON induces a sex-related response in food intake, weight gain, and biochemical parameters in peripubertal rats.•Hematological, histological, and oxidative stress response to DON is not sex-dependent in peripubertal rats.•DON nephrotoxicity is modulated by an oxidative stress response.
ABSTRACT Vomiting and diarrhea are two important clinical signs that can cause significant electrolytic and acid-base imbalances. The purposes of this study were to characterize hydric, electrolytic ...and acid-base disorders presented by puppies with hemorrhagic gastroenteritis and to compare the traditional and quantitative approaches to acid-base status interpretation. Sixty-one animals with a history of vomiting and/or diarrhea were used in this study and the following tests were performed: complete blood count, total plasma protein concentration and hemogasometry. Mean, standard deviation and Kappa values were calculated. The imbalances characterized by both approaches were: 42 (69%) animals without imbalance, 17 (28%) with metabolic alkalosis and 2 (3%) with metabolic acidosis by the traditional approach and 17 (28%) dogs without imbalance, 26 (43%) with metabolic alkalosis and 18 (29%) with metabolic acidosis by the quantitative approach. The agreement calculated between two approaches coincide in 28 cases, with a moderate Kappa value equivalent to 0.459. The most found imbalances were metabolic alkalosis, hypokalemia, and mild dehydration. Most of acid-base disturbances were not identified by the traditional approach, whereas by the quantitative approach, they were easily determined. Thus quantitative approach proved to be superior in identification of possible acid-base imbalances.
RESUMO Vômito e diarreia são dois sinais clínicos importantes, que podem causar desequilíbrios eletrolíticos e ácido-base importantes. Os objetivos deste trabalho foram caracterizar os desequilíbrios hídrico, eletrolítico e ácido-base apresentados por filhotes de cães com gastroenterite hemorrágica e comparar as abordagens de interpretação do equilíbrio ácido-base tradicional e quantitativa. Sessenta e um animais com histórico de vômito e/ou diarreia foram utilizados neste estudo, e os seguintes testes foram realizados: hemograma, concentração de proteína total plasmática e hemogasometria. Média, desvio-padrão e valor de Kappa foram calculados. Os desequilíbrios caracterizados pelas duas abordagens foram: 42 (69%) animais sem desequilíbrio, 17 (28%) com alcalose metabólica e dois (3%) com acidose metabólica, pela abordagem tradicional, e 17 (28%) cães sem desequilíbrio, 26 (43%) com alcalose metabólica e 18 (29%) com acidose metabólica, pela abordagem quantitativa. A concordância calculada entre as duas abordagens coincidiu em 28 casos, com um valor de Kappa moderado, equivalente a 0,459. Os desequilíbrios mais encontrados foram alcalose metabólica, hipocalemia e desidratação leve. A maioria dos distúrbios não foram identificados pela abordagem tradicional, enquanto, pela abordagem quantitativa, foram facilmente determinados. Portanto, a abordagem quantitativa provou-se superior na identificação de possíveis desequilíbrios ácido-base.
PDF
