A simple method for screening antimicrobial compounds with application to plant disease and fruit quality

Aims:  It is often difficult to extrapolate information from a Petri dish and apply it to commercial applications as with antimicrobial assays. Often large volumes of commodities are used for a virtually untested protocol and result in an unnecessary expenditure of time and materials. An intermediate method, where experimental compounds could be tested directly on a specific commodity without expending large quantities of either sample or compound, would be practical and economical.
Methods and Results:  A method was developed that employs the use of a small experimental chamber in which pieces of natural materials (e.g. fruit) can be tested with antimicrobial compounds. This method uses a type of autoclavable incubation chamber with a filter paper base, hydrating sponge pieces and a sterile glass sample platform. The chamber offers a sterile, controlled environment and can be manipulated to serve a number of studies.
Conclusion:  The chamber results are more analogous to what happens on whole fruit than the Petri dish.
Significance and Impact of the Study:  This method is presently used to screen for antimicrobial compounds and treatments needed to control serious economic pests compromising Florida's agriculture.     

Dependence of alignment direction on magnitude of strain in esophageal smooth muscle cells

The response of cells in vitro to mechanical forces has been the subject of much research using devices to exert controlled mechanical stimulation on cultured cells or isolated tissue. In this study, esophageal smooth muscle cells were seeded on flexible polyurethane membranes to form a confluent cell layer. The cells were then subjected to uniform cyclic stretch of varying magnitudes at a frequency of approximately five cycles per minute in a custom made mechatronic bioreactor, providing similar strains experienced in the in vivo mechanical environment of the esophagus. The results show that the orientation response is dependent on the magnitude of cyclic stretch applied. Smooth muscle cells showed parallel alignment to the force direction at low cyclic strains (2%) compared to the hill‐valley morphology of static controls. At higher strains (5% and 10% magnitude), the cells exhibited a consistent alignment perpendicular to the strain. To our knowledge, this is the first time that the alignment direction's dependence on strain magnitude has been demonstrated. MTS analysis indicated that cell metabolism was reduced when mechanical strain was applied, and proliferation was inhibited by mechanical strain. Protein expression indicates a decrease in smooth muscle α‐actin, indicative of changes in cell phenotype, an increase in vimentin, which is associated with increased cell motility, and an increase in desmin, indicating differentiation in stimulated cells. Biotechnol. Bioeng. 2009;102: 1703–1711. © 2008 Wiley Periodicals, Inc.     

Effect of Heliothis subflexa herbivory on fruit abscission by Physalis species: the roles of mechanical damage and chemical factors

1. Insect oral secretions are important for the induction of a number of plant responses, but the relative role of mechanical damage in the induction of these responses is often not well understood. Damage from the frugivore Heliothis subflexa, a specialist on Physalis species, causes herbivore‐induced fruit abscission. In this field study, we examined the separate and combined effects of mechanical damage and H. subflexa oral secretions on Physalis fruit abscission. 2. To determine the relative role of mechanical and chemical factors, the following treatments were administered to fruit: (1) three levels of mechanical damage, (2) natural herbivore damage by control larvae and by larvae surgically treated to inhibit saliva secretion, and (3) injection of H.subflexa oral secretions and a water control. Abscission of mechanically damaged fruit with and without the addition of oral secretions was also compared. 3. Mechanical damage was sufficient to cause fruit abscission, and the addition of oral secretions to mechanically damaged fruit did not cause an increase in fruit abscission. Normal caterpillars and those treated to inhibit saliva secretion caused similar abscission rates. 4. Though most studies examining the effects of insect oral secretions on induced plant responses find these chemical stimuli to be important or essential, the results of the present study showed that oral secretions are not necessary for fruit abscission. Future work is needed to determine the relative importance of mechanical damage in herbivore‐induced plant responses in other systems.     

Proteomics for the detection of indirect markers of steroids treatment in bovine muscle

Despite the ban by the European Union, anabolic steroids might still be illicitly employed in bovine meat production. The surveillance of misuse of such potentially harmful molecules is necessary to guarantee consumers’ health. Analytical methods for drug residue control are based on LC‐MS/MS, but their efficacy can be hindered due to undetectable residual concentrations as a result of low‐dosage treatments. Screening methods based on the recognition of indirect biological effects of growth promoters’ administration, such as the alteration of protein expression, can improve the efficacy of surveillance. The present study was aimed at identifying modifications in the muscle protein expression pattern between bulls treated with an ear implant (Revalor‐XS®) containing trenbolone acetate (200 mg) and estradiol (40 mg), and untreated animals. The analysis of skeletal muscle was carried out using a tandem mass tags shotgun proteomics approach. We defined 28 candidate protein markers with a significantly altered expression induced by steroids administration. A subset of 18 candidate markers was validated by SRM and allowed to build a predictive model based on partial least square discriminant analysis. Our findings confirm the effectiveness of the proteomics approach as potential tool to overcome analytical limitations of drug residue monitoring.     

Integrating flood depth and plant resistance with chlorantraniliprole seed treatments for management of rice water weevil,Lissorhoptrus oryzophilus (Coleoptera: Curculionidae)

Chlorantraniliprole seed treatments in rice provide effective suppression of rice water weevil populations in the United States; however, heavy reliance on prophylactic insecticide treatments as a sole strategy could destabilize management programs for this insect. The present research evaluated the compatibility of seed treatments with two other potential management tactics—plant resistance and shallow flooding–by conducting two split‐plot experiments in 2009 and 2011. In both experiments, no substantial antagonism was found among the 3 different tactics. Statistical interactions in these experiments arose from the strong and persistent effects of chlorantraniliprole on larval densities rather than incompatibility of tactics. In 2009, weevil densities differed among varieties and were significantly lower on the cultivar “Jefferson.” In 2011, weevil densities were reduced significantly in shallow‐flooded plots compared to deep‐flooded plots. Significant reductions in weevil numbers by chlorantraniliprole seed treatments, even at application rates 5 fold lower than commercially recommended rates, demonstrated the potential to reduce application rates of this highly potent larvicide. These latter results suggest that future studies on the relationship between chlorantraniliprole seed treatment rate and weevil fitness are warranted.     

混合痔手术治疗技术新进展

：痔(Haemorrhoids)是直肠末端黏膜、肛管皮肤下痔静脉丛屈曲或扩张而形成的柔软静脉团,是外科常见的疾病。尽管保守治 疗适用于大部分患者人群,但是手术治疗却适用于大部分严重病人,比如外剥内扎术就被视为治疗IV 度痔的金标准。痔的手术 治疗有传统手术和微创手术,为了减轻患者的痛苦、加速恢复、减少并发症的发生,PPH 和TST 等新型手术方式也逐渐被应用于 III痔的治疗中,这些手术方法的目的是纠正痔疮的病因及病理生理基础,具有微创、痛苦小的特点,但往往复发率较高。随着手术 方式的改进以及操作技术的成熟,痔的外科治疗效果也取得了长足的进步。本文对混合痔的外科手术技术作一综述,为临床治疗 提供理论依据。     

Dynamic 3D culture: Models of chondrogenesis and endochondral ossification

The formation of cartilage from stem cells during development is a complex process which is regulated by both local growth factors and biomechanical cues, and results in the differentiation of chondrocytes into a range of subtypes in specific regions of the tissue. In fetal development cartilage also acts as a precursor scaffold for many bones, and mineralization of this cartilaginous bone precursor occurs through the process of endochondral ossification. In the endochondral formation of bones during fetal development the interplay between cell signalling, growth factors, and biomechanics regulates the formation of load bearing bone, in addition to the joint capsule containing articular cartilage and synovium, generating complex, functional joints from a single precursor anlagen. These joint tissues are subsequently prone to degeneration in adult life and have poor regenerative capabilities, and so understanding how they are created during development may provide useful insights into therapies for diseases, such as osteoarthritis, and restoring bone and cartilage lost in adulthood. Of particular interest is how these tissues regenerate in the mechanically dynamic environment of a living joint, and so experiments performed using 3D models of cartilage development and endochondral ossification are proving insightful. In this review, we discuss some of the interesting models of cartilage development, such as the chick femur which can be observed in ovo, or isolated at a specific developmental stage and cultured organotypically in vitro. Biomaterial and hydrogel‐based strategies which have emerged from regenerative medicine are also covered, allowing researchers to make informed choices on the characteristics of the materials used for both original research and clinical translation. In all of these models, we illustrate the essential importance of mechanical forces and mechanotransduction as a regulator of cell behavior and ultimate structural function in cartilage. Birth Defects Research (Part C) 105:19–33, 2015. © 2015 Wiley Periodicals, Inc.     

Effect of adding nano‐titanium dioxide on the microstructure,mechanical properties and in vitro bioactivity of a freeze cast merwinite scaffold

In the present research, merwinite (M) scaffolds with and without nano‐titanium dioxide (titania) were synthesized by water‐based freeze casting method. Two different amounts (7.5 and 10 wt%) of n‐TiO₂ were added to M scaffolds. They were sintered at temperature of 1573.15°K and at cooling rate of 4°K/min. The changes in physical and mechanical properties were investigated. The results showed that although M and M containing 7.5 wt% n‐TiO₂ (MT7.5) scaffolds had approximately the same microstructures in terms of pore size and wall thickness, these factors were different for sample MT10. In overall, the porosity, volume and linear shrinkage were decreased by adding different weight ratios of n‐TiO₂ into the M structure. According to the obtained mechanical results, the optimum mechanical performance was related to the sample MT7.5 (E = 51 MPa and σ = 2 MPa) with respect to the other samples, i.e.: M (E = 47 MPa and σ = 1.8 MPa) and MT10 (E = 32 MPa and σ = 1.4 MPa). The acellular in vitro bioactivity experiment confirmed apatite formation on the surfaces of all samples for various periods of soaking time. Based on cell study, the sample which possessed favorable mechanical behavior (MT7.5) supported attachment and proliferation of osteoblastic cells. These results revealed that the MT7.5 scaffold with improved mechanical and biological properties could have a potential to be used in bone substitute. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:550–556, 2015     

Controlling network topology and mechanical properties of co‐assembling peptide hydrogels

Oligopeptides are well‐known to self‐assemble into a wide array of nanostructures including β‐sheet‐rich fibers that when present above a critical concentration become entangled and form self‐supporting hydrogels. The length, quantity, and interactions between fibers influence the mechanical properties of the hydrogel formed and this is typically achieved by varying the peptide concentration, pH, ionic strength, or the addition of a second species or chemical cross‐linking agent. Here, we outline an alternative, facile route to control the mechanical properties of the self‐assembling octa‐peptide, FEFEFKFK (FEKII); simply doping with controlled quantities of its double length peptide, FEFEFKFK‐GG‐FKFKFEFE (FEKII18). The structure and properties of a series of samples were studied here (0–100 M% of FEKII18) using Fourier transform infrared, small angle X‐ray scattering, transmission electron microscopy, and oscillatory rheology. All samples were found to contain elongated, flexible fibers and all mixed samples contained Y‐shaped branch points and parallel fibers which is attributed to the longer peptide self‐assembling within two fibers, thus creating a cross‐link in the network structure. Such behavior was reflected in an increase in the elasticity of the mixed samples with increasing quantity of double peptide. Interestingly the elastic modulus increased up to 30 times the pure FEKII value simply by adding 28 M% of FEKII18. These observations provide an easy, off‐the‐shelf method for an end‐user to control the cross‐linked network structure of the peptide hydrogel, and consequently strength of the hydrogel simply by physically mixing pre‐determined quantities of two similar peptide molecules. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 669–680, 2014.