Extended-spectrum beta-lactamases-producing gram-negative bacteria in companion animals: action is clearly warranted!     

Ewers C  Grobbel M  Bethe A  Wieler LH  Guenther S 《Berliner und Münchener tier?rztliche Wochenschrift》2011,124(3-4):94-101

Extended-spectrum beta-lactamases (ESBL)-producing Gram-negative bacteria pose a serious threat to Public Health in human medicine as well as increasingly in the veterinary context worldwide. Several studies reported the transmission of zoonotic multidrug resistant bacteria between food-producing animals and humans, whilst the contribution of companion animals to this scenario is rather unknown. Within the last decades a change in the social role of companion animals has taken place, resulting in a very close contact between owners and their pets. As a consequence, humans may obtain antimicrobial resistant bacteria or the corresponding resistance genes not only from food-producing animals but also via close contact to their pets.This may give rise to bacterial infections with limited therapeutic options and an increased risk of treatment failure. As beta-lactams constitute one of the most important groups of antimicrobial agents in veterinary medicine, retaliatory actions in small animal and equine practices are urgently needed. This review addresses the increasing burden of extended-spectrum beta-lactam resistance among Enterobacteriaceae isolated from companion animals. It should emphasize the urgent need for the implementation of antibiotic stewardship as well as surveillance and monitoring programs of multi resistant bacteria in particular in view of new putative infection cycles between humans and their pets.  相似文献   

Size Dependence of Structural Metastability in Semiconductor Nanocrystals     

CC Chen  AB Herhold  CS Johnson  AP Alivisatos 《Science (New York, N.Y.)》1997,276(5311):398-401

The kinetics of a first-order, solid-solid phase transition were investigated in the prototypical nanocrystal system CdSe as a function of crystallite size. In contrast to extended solids, nanocrystals convert from one structure to another by single nucleation events, and the transformations obey simple unimolecular kinetics. Barrier heights were observed to increase with increasing nanocrystal size, although they also depend on the nature of the nanocrystal surface. These results are analogous to magnetic phase transitions in nanocrystals and suggest general rules that may be of use in the discovery of new metastable phases.  相似文献   

Synergistic Effect of Porcine Follicular Fluid and Dibutyryl Cyclic Adenosine Monophosphate on Development of Parthenogenetically Activated Oocytes from Pre‐Pubertal Gilts     

AB Nascimento  MS Albornoz  L Che  JA Visintin  V Bordignon 《Reproduction in domestic animals》2010,45(5):851-859

This study investigated the effect of porcine follicular fluid (PFF) and dibutyryl cyclic adenosine monophosphate (dbcAMP) during in vitro maturation (IVM) of porcine oocytes on meiotic maturation, fertilization and embryo development, and compared the effect of supplementing the embryo culture media with PFF or foetal bovine serum (FBS) on embryo development. Oocytes from pre‐pubertal gilts were IVM for 44 h, and parthenogenetically activated or in vitro‐fertilized. Embryos were cultured in porcine zygote medium (PZM3) for 7 days. Cleavage and blastocyst rates were evaluated at 48 h and 7 days of culture. The supplementation of the IVM medium with 25% PFF and 1 mm dbcAMP for the first 22 h resulted in more (p < 0.05) embryos developing to the blastocyst stage as compared with the inclusion of dbcAMP alone. The dbcAMP + PFF combination increased (p < 0.05) the average number of nuclei per blastocyst as compared with either of these components alone or in its absence. A synergistic effect of dbcAMP + PFF during IVM was also reflected in the capacity of oocytes to regulate sperm penetration and prevent polyspermy, as twice as many oocytes from the control group were penetrated by more than one sperm as compared with those matured in the presence of both dbcAMP and PFF. The supplementation of PZM3 with 10% FBS from days 5 to 7 of culture significantly improved the total cell quantity in embryos derived either from control or dbcAMP + PFF matured oocytes. There was no effect on the total cell quantity when FBS was replaced by the same concentration of PFF. These studies showed that dbcAMP, PFF and FBS can improve both the quantity (57.3% vs 41.5%) and quality (74.8 vs 33.3 nuclei) of porcine blastocysts derived from oocytes recovered of pre‐pubertal gilts.  相似文献   

Probability of surface fire spread in Brazilian rainforest fuels from outdoor experimental measurements     

Guenther Carlos Krieger Filho  Paulo Bufacchi  José Carlos Santos  Carlos Alberto Gurgel Veras  Ernesto C. Alvarado  William Mell  João Andrade CarvalhoJr. 《European Journal of Forest Research》2017,136(2):217-232

This paper describes the development of a logistic model to predict the probability of surface fire spread in Brazilian rainforest fuels from outdoor experimental measurements. Surface fires spread over litter composed mostly of dead leaves and twigs. There were 72 individual outdoor experiments in eighteen sites. The fire propagated in 49% of the experiments. In each experiment, the litter height, litter temperature, unburned litter mass, wet and dry litter mass, soil temperature, wet and dry soil mass, ambient wind velocity, ambient air temperature, ambient air relative humidity and duration of fire spread were measured. Using these data, the rate of fire spread, litter bulk density, litter and soil moisture content, litter load and litter residue fraction were determined. For the sake of analysis, experimental results were classified into two groups: one for which the fire propagated and the other one for which the fire self-extinguished. Analyses of a logistic regression model showed that the relevant parameters for fire propagation are litter height and litter moisture content. Concerning the probability of successful fire propagation, the model showed a true positive rate of 71% and a true negative rate of 84%. The outdoor experiments also served to gather data to improve the understanding of surface fires and to provide input data for future computer simulations.  相似文献   

Temporal variability in basal isoprene emission factor     

Geron C  Guenther A  Sharkey T  Arnts RR 《Tree physiology》2000,20(12):799-805

Seasonal variability in basal isoprene emission factor (&mgr;g C g(-1) h(-1) or nmol m(-2) s(-1), leaf temperature at 30 degrees C and photosynthetically active radiation (PAR) at 1000 &mgr;mol m(-2) s(-1)) was studied during the 1998 growing season at Duke Forest in the North Carolina Piedmont. Emissions from eight upper-canopy white oak (Quercus alba L.) leaves were measured periodically from the onset of isoprene emission on Day of Year (DOY) 119 (April 29) to leaf senescence in late October (DOY 299). Emissions from four leaves were measured under basal conditions with a controlled-environment cuvette system equipped with 10-ml gas-tight syringes and a reduction gas detector. Emissions from the other four leaves were measured under ambient conditions with the same system. Emission rates from the four leaves measured under ambient conditions were adjusted to basal conditions based on the PAR and leaf temperature algorithms of Guenther et al. (1993). The seasonal onset of isoprene emission was in agreement with previous studies where cumulative degree days from the date of the last spring frost were used to estimate bud break, leaf expansion, and increase in basal emission factor (EF). Between DOY 141 (May 21) and 240 (August 28), mean meteorological conditions 6 to 18 h prior to the EF measurements (ambient PAR and temperature) explained up to 78% of the variability in mean basal EF between measurement periods. Summertime mean isoprene emission potential was reached on DOY 141 (May 21) and was maintained until DOY 240 (August 28), when isoprene emission began to decline monotonically as leaf senescence approached. The mean value for leaves measured under ambient conditions and adjusted to basal conditions for DOY 141-240 was 75.6 &mgr;g C g(-1) h(-1) (74.2-79.1), whereas the mean value for leaves measured under basal conditions was 72.9 &mgr;g C g(-1) h(-1) (64.7-88.9). Between DOY 141 and 240, daily mean isoprene EFs varied from 54 to 96 &mgr;g C g(-1) h(-1) (27 to 49 nmol m(-2) s(-1)). In agreement with previous work at this and other sites, basal isoprene emission rates of fully exposed leaves at the crown apex of this tree were about 20% higher than those of the selected leaves. The length of the period prior to measurement of isoprene emission, during which meteorology was correlated with basal EF, appeared to be related to the timing and periodicity of meteorological change, and probably explains quantitative differences in the length of this period among studies. The empirical equation that we derived for this effect explained variability in midday EFs at the study site, but its general applicability remains to be tested. Strong diurnal changes in EF (as high as a factor of 2) are implied in this study, and should be examined further.  相似文献   

Potential gene exchange between Bacillus thuringiensis subsp. kurstaki and Bacillus spp. in soil in situ     

Francesca Donnarumma  Donatella Paffetti  Guenther Stotzky  Cristina Vettori 《Soil biology & biochemistry》2010,42(8):1329-1337

The possible transfer of genes from Bacillus thuringiensis subsp. kurstaki (Btk) to indigenous Bacillus spp. was investigated in soil samples from stands of cork oak in Orotelli (Sardinia, Italy) collected 5 years after spraying of the stands with a commercial insecticidal preparation (FORAY 48B) of Btk. Two colonies with a morphology different from that of Btk were isolated and identified as Bacillus mycoides by morphological and physiological characteristics and by 16S rDNA analysis. Amplification by the polymerase chain reaction (PCR) of the DNA of the two isolated B. mycoides colonies with primers used for the identification of the Btk cry genes showed the presence of a fragment of 238 bp of the cry1Ab9 gene that had a similarity of 100% with the sequence of the cry1Ab9 gene present in GenBank, indicating that the isolates of B. mycoides acquired part of the sequence of this gene from Btk. No cells of Btk or B. mycoides carrying the 238-bp fragment of the cry1Ab9 gene were isolated from samples of unsprayed control soil. However, the isolates of B. mycoides were not able to express the partial Cry1Ab protein. Hybridization with probes for IS231 and the cry1Ab9 gene suggested that the inverted repeated sequence, IS231, was probably involved in the transfer of the 238-bp fragment from Btk to B. mycoides. These results indicate that transfer of genes between introduced Btk and indigenous Bacillus spp. can occur in soil under field conditions.  相似文献   

Transient phase-induced nucleation     

EB Sirota  AB Herhold 《Science (New York, N.Y.)》1999,283(5401):529-532

A transient metastable rotator phase occurring on crystallization of hexadecane into its triclinic phase from the supercooled melt was directly observed with time-resolved synchrotron x-ray scattering. In this system, the limit of supercooling (the crystallization temperature) is determined by the thermodynamic stability of the transient phase with respect to the liquid. The crystallization kinetics of the homologous series of n-alkanes was measured and explained in terms of a crossover from stability to "long-lived" metastability to transient metastability. This crossover allowed further confirmation of the nature of the transient phase.  相似文献   

氨基酸模型确定后肉仔鸡日粮中的最佳蛋白质供给   总被引：7，自引：0，他引：7  

刁其玉  霍启光  齐广海  Guenther K D  Mohme 《中国畜牧杂志》2000,36(3):25-27

试验用 540只罗曼肉仔鸡 ,分为 1 0个处理。研究同一氨基酸模型不同蛋白质水平对生长、饲料转化率、屠体组成和化学成分的影响。缘于氨基酸模型 ,日粮中蛋白含量自第 3周起从 2 3 %降低到1 9%,从第 5周起可降低到 1 7%对增重性能无明显负作用。饲料转化率显著地受日粮蛋白水平的影响。胴体的可食部分没有因日粮蛋白水平的降低而发生变化。腹脂因日粮蛋白水平而出现差异。机体的蛋白质和脂肪含量受日粮蛋白水平的影响 ,其含量为 :63 .4 4%～ 70 .2 5%;脂肪 :2 5.64 %～ 3 4 .92 %;干物质 :2 8.0 5%～ 3 0 .82 %。  相似文献   

ACQUIRED MEGAESOPHAGUS IN A HEIFER     

Uri  Bargai  AB  VMD  DVSc.  Ami Tsvi  Nathan  DVM  Shmuel  Pearl  DVM 《Veterinary radiology & ultrasound》1991,32(5):259-260

An 18-month-old pregnant heifer, hitherto normal, was noticed to regurgitate wet, partially digested roughage several times a day. On clinical examination, the heifer was losing body weight. There was no obstacle to passing a stomach tube to the rumen. A barium study of the esophagus was performed. Megaesophagus involving the cervical and cranial thoracic esophagus was diagnosed. Postmortem findings were a dilated esophagus, with no gross pathology seen. Histopathology showed extensive submucosal cellular infiltration of eosinophils. The classification and possible etilogy of the case is discussed.  相似文献   

Fertility Results after Vaginal Deposition of Frozen‐Thawed Buck Semen Diluted with Two Different Extenders Using One‐ or Two‐Step Procedures     

AB Nordstoga  L Söderquist  T Ådnøy  H Paulenz 《Reproduction in domestic animals》2011,46(1):82-86

In two field trials (T1 and T2), the effect of two different extenders for buck semen was tested. Semen from six (T1) and seven (T2) bucks of the Norwegian Dairy Goat breed was diluted either in a milk‐based extender containing egg yolk (M) or in a commercially available extender without egg yolk [Andromed^® (A)]. Dilution in M was performed in a two‐step procedure including centrifugation of the ejaculates and removal of the supernatant, while dilution in A was performed in one step. During the two trials (T1 and T2) 514 and 714, does, respectively, were artificially inseminated during natural oestrus, and the farmers performed the inseminations themselves after attending an artificial insemination (AI) training course. Vaginal insemination with 200 × 10⁶ spermatozoa diluted in M resulted in a 25‐day non‐return rate (NRR) and kidding rate of 37.3% and 24.5%, respectively, while semen diluted in A resulted in 31.7% NRR and a kidding rate of 19.8% (T1). In T2, NRR and kidding rate for AI performed with semen diluted with M were 42.7% and 28.5%, respectively, while dilution in A gave 37.2% NRR and a kidding rate of 26.8%. There was no significant effect of extender in the two trials [T1:p = 0.068 (NRR), p = 0.148 (kidding rate), T2:p = 0.096 (NRR), p = 0.38 (kidding rate)], but farmer had a significant effect on the fertility parameters in both trials. In conclusion, the present studies may indicate that Andromed^® is suitable for buck semen. However, more research is necessary to confirm the results and to improve the fertility of does after vaginal AI with frozen‐thawed semen.  相似文献