Treatment of solar prolapse using the heart bar shoe and dorsal hoof wall resection technique

This paper describes the treatment of 10 horses suffering from acute laminitis using the heart bar shoe and a dorsal hoof wall resection technique. All cases had progressed to prolapse of the tip of the pedal bone covered by solar corium through the horny sole; in one case the exposed tip of the distal phalanx became visible. Nine cases of distal phalangeal rotation and one case of distal displacement of the distal phalanx (sinking) are described. Two animals were destroyed because of the degree of lameness, one remains slightly lame at the trot and the remaining seven have returned to their previous use at comparable levels of performance.     

Tumour angiogenesis,anti‐angiogenic therapy and chemotherapeutic resistance

In order for a tumour to continue to grow and disseminate, it must acquire a new blood supply. Neovascularisation can be enacted by a number of different mechanisms. This dependence of tumour progression on an augmented vascular supply has been exploited by the development of anti‐angiogenic drugs, which are designed to inhibit new blood vessel formation or disrupt existing tumour‐associated vasculature, both leading to ischaemic–hypoxic tumour cell death. However, the clinical benefits of these therapeutic approaches are frequently variable and often transient, the neoplasm sometimes being able to use other neovascularisation mechanisms to maintain its blood supply and thus evade the current anti‐angiogenic therapy. Tumours may also develop a more malignant phenotype following this treatment. Clinical outcomes may be improved by simultaneously inhibiting different angiogenic pathways, abetted by more effective drug delivery regimens such as metronomic chemotherapy and the concurrent use of other antitumour modalities.     

The impact of bisphenol S on bovine granulosa and theca cells

Bisphenol S (BPS) is an endocrine‐disrupting chemical with multiple potential mechanisms of action, including as an oestrogen receptor agonist. BPS is increasingly used in plastics and thermal receipts as a substitute for bisphenol A, which has been phased out due to concerns about human health implications. The ability of BPS to alter female reproductive function in mammals has not been widely studied, despite the importance of normal hormone signalling for female reproduction. The aim of this study was to investigate how BPS (in a wide range of doses, including very low doses) affects granulosa cell and theca cell steroid hormone production and cell viability in the bovine. Granulosa cell oestradiol production was stimulated when cells were exposed to 100 μM BPS under basal conditions, but there was no effect of BPS when cells were stimulated with follicle‐stimulating hormone (FSH). Additionally, there was no effect of BPS on granulosa cell progesterone production or cell viability under basal or FSH‐stimulated conditions. BPS did not affect theca cell androstenedione or progesterone production, or theca cell viability under basal or luteinizing hormone‐stimulated conditions. This study suggests for the first time that BPS may alter oestradiol production by bovine granulosa cells, albeit at a concentration that is unlikely to be physiologically relevant. Further studies are needed to determine the effects of BPS on the bovine oocyte and on other functions of follicular cells.     

Antimicrobial residue detection in chicken yolk samples following administration to egg-producing chickens and effects of residue detection on competitive exclusion culture (PREEMPT) establishment

Competitive exclusion (CE) cultures may offer alternatives to antimicrobial agents for disease prophylaxis in poultry. To avoid potential transfer of antibiotic resistance, safe and effective CE cultures must, by necessity, be highly sensitive to antimicrobial residues. The following studies evaluated the effect of maternal administration of selected antibiotics on the establishment of a licensed CE culture, PREEMPT. Selected antibiotics were administered to actively laying hens for a period of 7 days (experiment 1) or 9 days (experiment 2) in drinking water [sulfadimethoxine (0.05%), enrofloxacin (0.005%), and tylosin tartrate (0.05%)] or feed (sulfadimethoxine with ormetoprim, 250 ppm). In experiment 1, fertile eggs were collected daily and subjected to bioassay for detectable antimicrobial residues in yolk. Antimicrobial residues were not detected during the 7 days of treatment or the subsequent 3 days following cessation of treatment in the control, sulfadimethoxine, sulfadimethoxine with ormetoprim, or tylosin treatment groups. However, detectable residues were observed in eggs derived from enrofloxacin-treated hens on days 6 and 7 during antibiotic administration and also on days 2 and 3 post-antibiotic administration. In experiment 2, antimicrobial residues were also only detected in yolks from hens treated with enrofloxacin. Residue detection occurred on days 2-6 of antibiotic administration, on day 9 of antibiotic administration, on days 1-3 post-antibiotic administration, and also on day 7 post-antibiotic administration. A subset of eggs from each experimental group, corresponding to days 2-6 of antibiotic administration, days 4-6 post-antibiotic administration, and days 14-16 post-antibiotic administration, were pooled for incubation, and chicks hatched from these pools of fertile eggs were treated with PREEMPT at hatch. When 48-h cecal propionate concentrations were used as an index of culture establishment, reduced (P < 0.05) efficacy was observed only in chicks derived from enrofloxacin-treated hens at either collection period. Although several antibiotics do not appear to produce detectable egg residues or interfere with CE culture establishment, these data suggest that chicks derived from enrofloxacin-treated hens may not be candidates for safe and effective CE culture treatment.     

The relevance of marine chemical ecology to plankton and ecosystem function: an emerging field

Marine chemical ecology comprises the study of the production and interaction of bioactive molecules affecting organism behavior and function. Here we focus on bioactive compounds and interactions associated with phytoplankton, particularly bloom-forming diatoms, prymnesiophytes and dinoflagellates. Planktonic bioactive metabolites are structurally and functionally diverse and some may have multiple simultaneous functions including roles in chemical defense (antipredator, allelopathic and antibacterial compounds), and/or cell-to-cell signaling (e.g., polyunsaturated aldehydes (PUAs) of diatoms). Among inducible chemical defenses in response to grazing, there is high species-specific variability in the effects on grazers, ranging from severe physical incapacitation and/or death to no apparent physiological response, depending on predator susceptibility and detoxification capability. Most bioactive compounds are present in very low concentrations, in both the producing organism and the surrounding aqueous medium. Furthermore, bioactivity may be subject to synergistic interactions with other natural and anthropogenic environmental toxicants. Most, if not all phycotoxins are classic secondary metabolites, but many other bioactive metabolites are simple molecules derived from primary metabolism (e.g., PUAs in diatoms, dimethylsulfoniopropionate (DMSP) in prymnesiophytes). Producing cells do not seem to suffer physiological impact due to their synthesis. Functional genome sequence data and gene expression analysis will provide insights into regulatory and metabolic pathways in producer organisms, as well as identification of mechanisms of action in target organisms. Understanding chemical ecological responses to environmental triggers and chemically-mediated species interactions will help define crucial chemical and molecular processes that help maintain biodiversity and ecosystem functionality.     

Retinoic acid induces apoptosis in activated canine neutrophils

Activated neutrophils live longer, produce toxic metabolites and cause considerable tissue injury, which is central to the pathogenesis of many inflammatory conditions. Retinoids are a class of lipophilic compounds with anti-inflammatory effects. We examined the effect of retinoic acid on apoptosis in normal and activated neutrophils. Our results showed that treatment with 1 μg/ml Escherichia coli lipopolysaccharide (LPS) for 12 and 36 h delayed the spontaneous neutrophil apoptosis compared to untreated cells. But exposure of LPS-treated cells to retinoic acid (1 and 5 μM) abolished the inhibitory effects of LPS on neutrophil apoptosis in a concentration-dependant manner based on annexin V staining, Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, light and electron microscopy. These results show that retinoic acid increases apoptosis in activated canine neutrophils and this effect could enhance the resolution of inflammation in vivo.     

Preliminary Studies on Cryopreservation of Common Tench (Tinca tinca) Embryos (Work in Progress)

Vitrification could provide a promising tool for the cryopreservation of fish embryos. However, to achieve cryopreservation using vitrification, chilling sensitivity and cryoprotectants toxicity were determined using tench embryos at four developmental stages (11, 17, 23 and 29 h). Embryos treated with alcalase (2 ml/998 ml, 2 min at 22°C) were exposed to chilling with/without warming. Other embryos were exposed to methanol and glycerol at the concentration of 10% and 20% for periods of 20 min. At last, embryos were incubated at special incubator cages where hatching rates were counted. Regarding chilling sensitivity and exposure to chilling followed by warming, the hatching rates of embryos decreased significantly (p < 0.001) after exposure to 0°C at all developmental stages except the 29-h stage compared with the controls. The embryo stage most sensitive to chilling was 11-h stage. The 29-h stage exhibited the least sensitivity to low temperature while 17-h and 23-h stages were intermediate in their sensitivity to chilling. The toxicity of methanol increased significantly (p < 0.001) with developmental stage for 11, 17 and 23-h stages. The highest hatching rates of tench embryos were obtained with 29-h embryos using various concentrations of methanol. The hatching rates of tench embryos exposed to glycerol concentrations were approximately similar to those embryos exposed to methanol concentrations except for 11-h embryos that showed no hatching. Unfortunately, we could not obtain living embryos in any of the conditions examined after vitrification. In conclusion, it was quite difficult to vitrify the tench embryos during this study using various vitrifying solutions and the method reported by Chen & Tian (2005) and further studies are needed to achieve successful cryopreservation.     

Covalently bridging gaps in single-walled carbon nanotubes with conducting molecules

Molecular electronics is often limited by the poorly defined nature of the contact between the molecules and the metal surface. We describe a method to wire molecules into gaps in single-walled carbon nanotubes (SWNTs). Precise oxidative cutting of a SWNT produces carboxylic acid-terminated electrodes separated by gaps of 相似文献