摘要:

The discovery in the early 1990s that progestin‐induced growth hormone (GH) excess in the dog originates in the mammary gland can be seen as a hallmark in the research on the pathogenesis of mammary cancer in the dog. The local biosynthesis and release of GH may provide a highly proliferative environment in the mammary gland, which contributes to the development and/or progression of mammary tumours.

ISSN:0165-2176    

DOI:10.1080/01652176.1999.9695004

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Mycotoxins contaminate various feed and food commodities, due to the global occurrence of toxinogenic molds. They exert adverse health effects in human and animals. The nature of these toxic effects varies depending on the chemical structure of the toxin. The degree of these adverse effects is not only determined by the toxin concentration present in foods and feeds, but also by the time of exposure. Whilst in animals, next to acute intoxication, losses in productivity, reduced weight gain and immunosuppression are considered as most important feature of mycotoxicoses, genotoxic effects and the involvement of certain mycotoxins such as aflatoxin, ochratoxins and fumonisins in the etiology of human cancers have obtained particular attention. This implies that recent research activities concentrate on mechanistic aspects of mycotoxin‐ induced pathologies, rather than compiling analytical measures of mycotoxin concentrations in food and feeds.

ISSN:0165-2176    

DOI:10.1080/01652176.1999.9695005

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Laminitis has been a recognized disease since early Greek and Roman times, but it is still bothering both practitioners and scientists. In the last decade a lot of new fundamental research has been done to elucidate the pathogenesis of laminitis. New insights into the pathogenesis, the predisposing factors (including nutritional overload, endotoxaemia, shock, management, etcetera), clinical and radiological signs, differential diagnosis, therapy, and prognosis of the disease are described. The data, however, are not always in agreement with each other, giving further proof of the complexity of the syndrome.

ISSN:0165-2176    

DOI:10.1080/01652176.1999.9695006

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Discussed are the outlines of a risk assessment‐based system of meat safety assurance to replace the current meat inspection. An example of a system that uses the Hazard Analysis of Critical Control Points (HACCP)‐principles in the entire production chain from stable to table is also given. Continuous evaluation of risks is the main driving force of the new system. Only then the system has the means to remain flexible and provide for the data necessary to convince trade partners that the products they buy are safe. A monitoring system that keeps track of the important health hazards in the entire chain from stable to table is therefore necessary. This includes monitoring of cases of disease in the human population caused by the hazardous agents of concern. Coordination of the monitoring and control and processing of the information is done by an independent body. Furthermore, the system demands a production from stable to table that is based on the ideas of Integrated Quality Control (IQC), HACCP, and certification of production processes and quality control procedures. Clear legislation provides for criteria about acceptable or unacceptable health risks for the consumer and determines at what moments which risks should be controlled by the producers. Simultaneously, the legislation has to be flexible enough to be able to adapt quickly to any changes in risks, or in the way risks should be controlled. In the new system current meat inspection can easily be carried out by employees of the slaughter houses and is no longer a direct responsibility of the authorities. The authorities only demand certain safety levels and verify whether producers stick to these. Producers remain fully responsible for the safety and quality of their products, and fully liable in case of any damage to the consumers’ health. However, it is to be expected that some EU Member‐States miss the organizational and agricultural basis for a successful application of the new system. Consequences are that two parallel flows of meat and meat products may come to existence. One flow will exist of meat produced according to the new, and with respect to safety assurance, superior system. The other flow will consist of meat produced and inspected in the traditional way. However, this meat will contain all the flaws that required a revision of the system in the first place. This, and the fact that EU policy ordains that part‐taking in an alternative meat inspection system should be voluntary, may very well result in a very slow start‐up of the new system. One of the easiest solutions, however, would be to implement a decontamination step in the slaughtering process, provided that this is accompanied by strict codes of hygienic practices and good manufacturing practices. Not only would this lead to safer meat, but also result in the two separate flows of meat becoming one flow again as well as an easier to organize livestock production according to HACCP‐principles.

ISSN:0165-2176    

DOI:10.1080/01652176.1999.9695007

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

ISSN:0165-2176    

DOI:10.1080/01652176.1999.9695008

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The capacitation process of sperm cells involves complex changes in the composition and orientation of molecules at the surface of the sperm cell. Here we focus on the lipid architecture in the sperm plasma membrane and demonstrate that the sperm plasma membrane is not static but is an extremely dynamic structure. Advanced fluoroscopic techniques enabled continuous monitoring of lipid organization in living cells and extremely rapid lipid movements were observed. The orientation of lipids in the sperm plasma membrane changed under capacitative treatments, was found to be sensitive for temperature and also changed upon binding of sperm cells to the zona pellucida. The changes in membrane properties coincided with an activation of protein kinases resulting in tyrosine phosphorylation of specific plasma membrane proteins. The detected membrane changes relate to intrinsic membrane properties such as fluidity, permeability, adhesiveness and fusibility. We think that these results may provide a physiological basis for new assays, able to discriminate between functional and non‐physiological sperm cells.

ISSN:0165-2176    

DOI:10.1080/01652176.1999.9695009

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

ISSN:0165-2176    

DOI:10.1080/01652176.1999.9695010

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The aim of this study was to gain knowledge of residue formation after the use of melengestrol acetate (MGA) as a growth‐promoting agent. Two Holstein‐Friesian heifers each received a daily dose through the feed of 0, 0.5 mg (2 heifers with and without withdrawal each), 1.5 mg or 5.0 mg MGA for 8 weeks. MGA residues in plasma were screened by enzyme immuno‐assay (EIA). Concentrations in kidney, liver, and muscle were quantified by liquid‐chromatography‐mass spectrometry (LC‐MS), and in fat by gas chromatography‐mass spectrometry (GC‐MS). MGA levels in plasma were 40, 128, and 280 ng/L, respectively. Residues accumulated in muscle and kidney (5‐fold), liver (20‐to‐40‐fold), and fat (200‐fold). After administration of 1.5 mg per day the mean MGA concentration in fat was 29 μg/kg and thus violated USA regulations which specify a limit of 25 ppb. Therefore the labelled use of MGA (0.5 mg per day) has to be officially controlled.

ISSN:0165-2176    

DOI:10.1080/01652176.1999.9695011

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The concentrations of serum amyloid A protein (SAA) and transferrin in blood samples from broilers in various stages of naturalStaphylococcus aureusinfection, from healthy counterparts, and from turpentine‐ or saline‐injected pullets were measured using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE), immunoblotting, and densitometry. SAA was not detected in healthy chickens but was detected in turpentine‐injected pullets and inS. aureus‐infected broilers. Relative percentages of transferrin in turpentine‐ and saline‐injected pullets were not different. Broilers with aS. aureusinfection had a two‐fold higher transferrin level than did their unaffected counterparts. There was also a difference between the transferrin levels of healthy broilers and healthy pullets, which indicates that other variables, such as breed or breeding conditions, may influence the transferrin level. This preliminary study showed that SAA is an acute‐phase protein and a more reliable variable for diagnosing lesions in chickens than transferrin.

ISSN:0165-2176    

DOI:10.1080/01652176.1999.9695012

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This mini‐review highlights new information on various research aspects presented by specialists from all over the world at the 4th Pestivirus meeting held in Giessen (Germany) from March 15–19, 1999. Especial attention is paid towards differences in humeral and cellular immune response of naive and persistently infected calves with BVDV, and towards BVD eradication programmes m the Scandinavian countries.

ISSN:0165-2176    

DOI:10.1080/01652176.1999.9695013

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor