Effect of therapeutic administration of β-lactam antibiotics on the bacterial community and antibiotic resistance patterns in milk

Dairy cows with mastitis are frequently treated with antibiotics. The potential effect of antibiotics on the milk microbiome is still not clear. Therefore, the objective of this research was to investigate the effect of 2 commonly used cephalosporins on the milk microbiota of dairy cows and the antibiotic resistance genes in the milk. The milk samples were collected from 7 dairy cows at the period before medication (d 0), medication (d 1, 2, 3), withdrawal period (d 4, 6, 8), and the period after withdrawal (d 9, 11, 13, 15). We applied 16S rRNA sequencing to explore the microbiota changes, and antibiotic resistance patterns were investigated by quantitative PCR. The microbiota richness and diversity in each sample were calculated using the Chao 1 (richness), Shannon (diversity), and Simpson (diversity) indices. The cephalosporins treatment lowered the Simpson diversity value at the period of withdrawal. Members of the Enterobacter genera were the most affected bacteria associated with mastitis. Meanwhile, antibiotic resistance genes in the milk were also influenced by antibiotic treatment. The cephalosporins treatment raised the proportion of bla_TEM in milk samples at the period of withdrawal. Therefore, the treatment of cephalosporins led to change in the milk microbiota and increase of β-lactam resistance gene in the milk at the time of withdrawal period.     

Proteome changes during pork meat ageing following use of two different pre-slaughter handling procedures

The influence of postmortem storage time and pre-slaughter conditions (transport the day before slaughter or immediately before slaughter) on proteome changes of pork meat was investigated over a 72 h ageing period. Intensities of 37 spots varied significantly (p<0.05) with ageing time. Changes indicated proteolysis of troponin T, actin, -crystallin, myokinase, creatine kinase and mitochondrial ATPase, but also of proteins constitutive of the Z-lines, namely cypher proteins and myozenin. Other modifications were the intensity increase of a full-length protein of the sarcoplasmic reticulum, which may be linked to its increased extractibility after membrane disruption, and a gradual shift in pHi towards alkaline values of some forms of myosin light chains (MLC) 2 and 3. The pre-slaughter conditions affected significantly (p<0.05) 8 spots. Mitochondrial ATPase was over-expressed in the group transported immediately before slaughter, also characterised by a faster pH fall, and the shift in pHi of MLC 2 was more pronounced. The pre-slaughter conditions had no significant effect on the above proteolytic events.     

Immunocytological detection of salivary mucins (MUC5B) on the mucosal pellicle lining human epithelial buccal cells

The mucosal pellicle is defined as the protein film adsorbed onto oral mucosa. This study aimed at characterizing the ultrastructure of human epithelial buccal cells and localizing salivary mucins MUC5B, a major constituent of the mucosal pellicle. Cells were sampled from the buccal surface and prepared for Transmission Electron Microscopy using high‐pressure freezing/cryosubstitution followed by immunogold labelling of MUC5B. Morphologically, cells were visualized as typical cells of the superficial layer of a squamous nonkeratinized epithelium with a partly degraded plasma membrane. The outer surface of the plasma membrane was lined with a biological material of medium electron density. MUC5B were detected in the extracellular space, and particularly in the vicinity of the plasma membrane, sometimes onto fibrils protruding from the membrane. This area was, therefore, considered as constituting the mucosal pellicle, which appeared as a mixed film of both salivary and epithelial components. The distribution of gold particles suggested that the surface of the pellicle was not uniform, and that the film thickness could reach up to 100 nm. This work showed the feasibility of visualizing and characterizing the mucosal pellicle directly on human epithelial buccal cells sampled in a noninvasive manner. Microsc. Res. Tech. 77:453–457, 2014. © 2014 Wiley Periodicals, Inc.     

西藏喜马拉雅山边缘的地壳结构及其变化

西藏雅鲁藏布江缝合线南部壳—幔边界的广角反射剖面,揭示了喜马拉雅山之北连续莫霍界面的深度(70公里),而向前莫霍界面的深度要浅15公里.再往南从35公里深度来的反射波是来自印度半岛的莫霍界面.     

Single-layer cylindrical compaction

In VLSI compaction, an array composed of a single cell warrants special consideration. Standard methods of compaction [MS] result in either nonuniform cell layouts or unnecessarily large cell spacing. These inadequacies would be lessened were the array compacted instead by compacting a single instance of the cell against itself: in essence, the cell would be compacted on a torus. Equivalently, the problem becomes that of compacting a layout to fit into a minimal area shape 4-tiling the plane.Only the one-dimensional version of the problem has been addressed: that equivalent to compaction on a cylinder. Unfortunately, the efficient longest-path approach to one-dimensional compaction is not directly applicable since there is no origin to compact against. Eichenberger and Horowitz solve the problem in polynomial time by using a min-cost flow approach to assign positions to the nodes of a constraint network embedded on a cylinder [EH]. Mehlhorn and Rülling found an iterative approach running in timeO(n ² logn) when restricted to networks abstracted from layouts having any fixed number of layers [MR]. In this paper the longest-path approach is adapted to solve the same cylindrical compaction problem on planar networks—those abstracted from single-layer layouts—in justO(n logn) time.This research was supported by NSF Presidential Young Investigator Grant MIP-8657693.     

In vivo compartmental metabolism of13C docosahexaenoic acid,studied by gas chromatography-combustion isotope ratio mass spectrometry

The exchange of docosahexaenoic acid (22:6n-3) within lipid pools in rat and human has been followed as a function of time after the ingestion of triglycerides (TG) containing 22:6n-3 labeled with¹³C(¹³C 22:6n-3). The¹³C abundance in the fatty acid was measured by gas-chromatography-combustion isotope ratio mass spectrometry which allowed the detection of 0.001 atom¹³C percent¹²C. The¹³C 22:6n-3 appearance was rapid in the TG of very low density lipoprotein plus chylomicron fraction, in which the maximal labeling was observed at 3 and 2 h after ingestion in rat and human, respectively. Concomitant with the TG utilization of this fraction by lipoprotein lipase from tissues, unesterified¹³C 22:6n-3 appeared in the plasma albumin.¹³C 22:6n-3 bound to albumin was mostly present in unesterified form before 12 h post-ingestion while after that period, lysophosphatidylcholine (lysoPC) bound to albumin carried higher¹³C 22:6n-3 concentrations. These lyso-PC were mostly from hepatic origin and might represent a potential source of 22:6n-3 redistribution to tissues. The¹³C 22:6n-3 uptake into rat brain PC and phosphatidylethanolamine was still increasing when the concentration of plasma unesterified¹³C 22:6n-3 had already dropped to a minimal plateau value and during the period of maximal plasma circulation of¹³C 22:6n-3-lysoPC bound to albumin. In contrast, the uptake of¹³C 22:6n-3 into blood platelet PC occurred during the phase of important circulation of¹³C-22:6n-3 bound to albumin, suggesting thein vivo efficiency of the Lands pathway for this fatty acid. It is concluded that¹³C 22:6n-3 esterified in TG is rapidly absorbed and redistributed within plasma lipoproteins and that its redistribution within the two lipid species bound to albumin might influence its uptake by platelets and rat brain.     

Observational learning and the effects of model-observer similarity.

This study examined the effects of similarity in competence between model and observer on the effectiveness of observational learning in argumentative writing. Participants ( N=214, 8th grade, mixed ability) were assigned to 1 of 3 conditions: an observation/weak-focus, an observation/good-focus, or a control condition. The two observational-learning groups observed pairs of peer models performing writing tasks. Participants focused respectively on the noncompetent (weak) model or on the competent (good) model. The control group performed the writing tasks themselves. Results are consistent with the similarity hypothesis: Weak learners learn more from focusing their observations on weak models, whereas better learners learn more from focusing on good models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)