Novel Canine Tumour Suppressor Gene p53 Mutations in Cases of Skin and Mammary Neoplasms

Exons 4 to 8 of the tumour suppressor gene p53 were analysed in 25 skin and 25 mammary tumours of 50 dogs. A 1 bp deletion (ACCAC) was detected in codon 89 in exon 4 in a squamous cell carcinoma. A missense mutation CGCCAC (argininehistidine) was present in codon 162 in exon 5 in a mammary adenocarcinoma. Moreover, a silent mutation occurred in codon 103 (serine) of exon 4 in a mammary adenoma. The somatic nature of the three mutations was demonstrated.     

Novel p53 tumour suppressor mutations in cases of spindle cell sarcoma,pleomorphic sarcoma and fibrosarcoma in cats

Twenty feline neoplasms were sequenced in the region from exons 5 to 8 for the presence of tumour suppressor gene p53 mutations. In a spindle cell sarcoma of the bladder, a missense mutation (codon 164 AAGGAG, lysineglutamic acid) in exon 5 was detected. In a pleomorphic sarcoma, a 23 bp deletion involving the splicing junction between intron 5 and exon 6 was observed. In a fibrosarcoma, a 6 bp deletion of p53 covering 2 bp of exon 7 and 4 bp of intron 7, including the splicing junction, was found. The study demonstrates three new p53 mutations in different types of sarcomas in cats.     

Leukocyte and Cytokine Accumulation in the Ovine Teat and Udder during Endotoxin-Induced Inflammation

Persson Waller, K., Colditz, I.G., Flapper, P. and Seow, H.-F., 1997. Leukocyte and cytokine accumulation in the ovine teat and udder during endotoxin-induced inflammation. Veterinary Research Communications, 21 (2), 101-115The accumulation of leukocytes, ovine serum albumin and the cytokines interleukin-1 (IL-1), tumour necrosis factor- (TNF-), interleukin-8 (IL-8), granulocyte-macrophage colony-stimulating factor (GM-CSF) and interferon- (IFN-) was studied during endotoxin-induced inflammation in lactating and dry ovine udders, and in the teat cisterns of dry ewes after surgical closure of the passage between the teat and udder cisterns. Samples were taken before infusion and hourly up to 10 h after infusion of 0.1, 1 or 10 µg of endotoxin, or infusion of pyrogen-free saline (PFS) as a control. Rectal temperatures were measured.A significant dose- and time-dependent accumulation of leukocytes, mainly neutrophils, was observed in the lactating udders and in the teat cisterns. In the dry udders, the leukocyte accumulation was significant for time but not for dose. Peak numbers of cells were reached at 3-4 h in the dry udders and in the teat cisterns, but not until 10 h after infusion in the lactating udders. The changes in the ovine serum albumin concentrations mostly paralleled changes in leukocyte numbers.A role was indicated for TNF-, IL-8 and GM-CSF, but not for IL-1 and IFN-, during endotoxin-induced inflammation in the ovine udder. Release of TNF-, IL-8 and GM-CSF was most prominent in lactating udders, peaking at 2 or 3 h after infusion, but was also detected in dry udders and teat cisterns. Detectable levels of IL-1 and IFN- were occasionally found in all three groups.     

Plasma,Urinary and Biliary Residues in Cattle Following Intramuscular Injection of Nortestosterone Laurate

The synthetic androgen 19-nortestosterone (-NT) has been used illegally as a growth promoter in cattle production in the European Union. Elimination of -NT and its metabolites in plasma, urine and bile was studied in three cattle with cannulated gallbladders following intramuscular injection at a single site of 500 mg of the laurate ester (NTL) containing 300.5 mg -NT. Using enzyme immunoassay quantification, plasma Cmax of free -NT was 0.5±0.15 g/L (mean±SEM). Concentrations of free -NT in plasma were consistently greater than the assay limit of quantification (0.12 g/L) for 32.7±13.42 days. Mean residence time for free -NT in plasma was 68.5±20.75 days. Following sample preparation by immunoaffinity chromatography, high-resolution GC-MS was used to quantify -NT and -NT in urine and bile. -NT was detected irregularly in urine from two of the three animals post injection. The principal metabolite present in the urine, -NT, was detected for 160.3±22.67 days post injection. Cmax for -NT in urine was 13.7±5.14 g/L. Mean urinary AUC0–183 days for -NT was 845.7±400.90 (g h)/L.In bile, -NT was the only metabolite detected for 174.3±8.67 days post treatment. Cmax for -NT in bile was 40.8±12.70 g/L and mean biliary AUC0–183 days for -NT was 1982.6±373.81 (g h)/L. Concentrations of -NT in bile samples were greater than those in urine samples taken at the same time. The mean ratio of biliary:urinary AUC0–183 days was 3.0±0.72. It is concluded that bile is a superior fluid for detection of -NT following injection of NTL, owing to the longer period during which residues may be detected after administration.     

Reduced Ovulatory and Oestrous Activity in Zebu Heifers Following Trypanosoma vivax Infection

This paper describes a study on the oestrous and ovarian activity and responses to prostaglandin F2 (PGF2) administration and artificial insemination in zebu heifers.Four cycling heifers were artificially infected with 5×106 Trypanosoma vivax organisms. Two heifers served as controls. Two injections of PGF2 were given 11 days apart, commencing at the peak of parasitaemia in the infected animals, followed by artificial insemination 72 and 96 h after the second administration of PGF2. Sera were analysed for progesterone by radioimmunoassay, while ovarian activity and oestrus were determined by rectal palpation and visual observation, respectively. All the infected heifers developed the clinical disease. All control and infected heifers had progesterone profiles consistent with luteolysis and the occurrence of oestrus following the second administration of PGF2. Progesterone levels did not return to normal luteal values in infected animals, however, whilst they did so in control animals. No control or infected heifers became pregnant.The findings suggest that PGF2 will induce a non- fertile oestrus in zebu heifers acutely infected with T. vivax. Re-ovulation is also inhibited within 22 days in a majority of infected animals.     

The phenomenon of stress: Concepts and mechanisms associated with stress-induced responses of the neuroendocrine system

Stress, stressors and the stress response are terms which represent concepts rather than oeing precisely definable. No single theory of stress has been universally accepted. Selye's General Adaptation Syndrome of stress remains the primary theory for the basis of stress research in food-producing animals; however, other concepts and theories have been developed. This paper reviews current theories and suggests that the complexity of research on stress in food-producing animals can be attributed to the lack of concrete theories and concepts regarding identifiable stressors, the endocrine responses stimulated by potential stressors and the complex and integrated biological changes in the neuro-endocrine system resulting from exposure to hypothesized stressors.     

Milk Protein Polymorphism in Kangayam Cattle

This paper reports the milk protein polymorphism, the allele frequencies of variants and the possible linkages among various combinations of milk protein phenotypes in the Kangayam cattle of south India. Milk samples from 156 Kangayam cows were typed by starch gel and polyacrylamide gel electrophoresis for caseins and whey proteins, respectively. All the four milk protein components studied, _s1-casein, -casein, -lactoglobulin and -lactalbumin, exhibited polymorphism with high allele frequencies of 0.9231±0.0151 for _s1-casein C, 0.9263±0.0148 for -casein A, 0.9135±0.0159 for -lactoglobulin B and a relatively high frequency of 0.6218±0.0275 for -lactalbumin A. The mean heterozygosity estimated over all the four milk protein loci was 0.2420. Genetic equilibrium was observed among all the loci studied, except -lactalbumin. Linkage analysis confirmed the non-independence between _s1- and -caseins and between caseins and -lactalbumin phenotypes.     

Evaluation of Synchronization of Oestrus Based on Gonadotrophin-releasing Hormone and Its Potential Use for Fixed-Time Breeding in Tuli Beef Cows

The objective of the experiment was to compare the reproductive post-partum performance of beef cows synchronized for oestrus using prostaglandin F₂ (PGF₂) alone or with a gonadotrophin-releasing hormone (GnRH)-based drug. Fifty-five post-partum lactating Tuli cows were randomly allocated to three groups. Two groups were synchronized using either two injections of PGF₂ (500 g Prosolvin per injection) given 11 days apart (group 1), or GnRH (12.5 g Receptal per injection) followed 6 days later by an injection of 500 g PGF₂ (group 2). The cows were bred by artificial insemination 12 h after they were observed in oestrus. Group 3 was synchronized as for group 2, but a second injection of GnRH was given 54 h after the PGF₂ injection, at which time the cows were bred by artificial insemination (AI) without detection of oestrus. Blood samples were taken from the cows in group 3 and analysed for progesterone concentration to establish which cows were cycling and in oestrus before and at the time of breeding. Detection of oestrus and breeding by AI was done over 60 days. There were no significant differences (p>0.05) among the three groups in the first service and total conception rates. The percentage of cows in oestrus within 10 days of the synchronization treatment was not significantly different (p>0.05) between groups 1 and 2. The progesterone concentrations in the cows in group 3 showed that only those that were cycling at the start of the experiment responded to the synchronization treatment and conceived after fixed-time breeding. These results suggest that combinations of PGF₂ and GnRH may be of value in synchronizing oestrus and controlling breeding in Tuli cows. However, the benefit might be greater if only cows that are known to be cycling are bred in this way.     

Identification of Functional α-Adrenoceptor Subtypes in the Bovine Female Genital Tract During Different Phases of the Oestrous Cycle

The concentration and functionality of the -adrenoceptor (-AR) subtypes in the genital tract of cyclic heifers were investigated. In each tissue sample, a single class of ₁-ARs was observed, whereas two distinct classes of ₂-ARs were discriminated: low-affinity (LA) and high-affinity (HA) ₂-ARs. Statistical analysis showed the presence of significantly (p < 0.05) higher concentrations of all -AR subtypes in the follicle than in the corpus luteum. No significant differences were found in the ovary or myometrium between the luteal and follicular phases. In the ovary, the density of ₁-ARs was significantly (p < 0.05) higher than that of ₂-ARs. By contrast, there were significantly (p < 0.05) more ₂-ARs than ₁-ARs in the myometrium. As far as ₂-ARs are concerned, LA ₂-ARs were significantly (p < 0.05) higher than HA ₂-ARs in all tested tissues. Competition studies suggested that the rank order of potency of antagonists for ₁-ARs was prazosin > phentolamine > yohimbine, whereas for ₂-ARs the order of potency was yohimbine phentolamine > prazosin. Functional assays performed on myometrium showed that noradrenaline, phenylephrine and clonidine elicited concentration-dependent contractions only in dioestrus and pro-oestrus preparations and that clonidine was more effective than phenylephrine as a contractile agent. It appeared that there were no significant modifications in -AR affinity or concentration during the different stages of bovine oestrous cycle, whereas the uterine spontaneous activity and the responsiveness to -adrenergic stimulation was strongly influenced by hormonal levels. The modifications of uterine contractility observed during the oestrous cycle may be related to modifications induced in the transductional mechanisms of -ARs.     

Localization of glycoconjugates in dog parotid gland by lectin histochemistry

Parotid glands from adult dogs were stained with a battery of seven horseradish peroxidase-conjugated lectins (PNA, UEA, LTA, DBA, SBA, WGA and ConA). In some cases (PNA and DBA) neuraminidase digestion was followed by lectin staining. Acinar cells contained conspicuous quantities of oligosaccharides with terminal sialic acid radicals. Galactosil-(13)N-acetylgalactosamine was the most abundant penultimate sugar linked toN-acetylneuraminic acid. Sialylated components having the terminal dimer sialic acid-N-acetylgalactosamine were found in the acinar cells. Secretory cells presented a heterogeneous distribution of glycoconjugates with terminal fucose and -N-acetylgalactosamine. Fucose,N-acetylglucosamine and -N-acetylgalactosamine were present on the apical cytoplasm and surface of the striated and interlobular duct cells. This glycosidic composition was unaffected by extensive selective breeding. The role of abundant amounts of sialic acid radicals in the oral mucosa was considered.Abbreviations HRP horseradish peroxidase - PBS phosphate-buffered saline see also Tables I and III     

Reflections on viruses and cancer

In recent years human and animal cancers have increasingly been shown to have a viral component in their aetiology. Oncogenic viruses will continue to be discovered although with certain cancers there is also an important environmental component, and with others — congenital cancers and cancers of early childhood — an important genetic component. There is thus the probability that cancer may not be an entity. Rather it may be a syndrome, the phenotypic expression of alteration of cellular metabolism, differentiation and cell death. More information is needed on the mathematics of cell division and destruction,in vivo andin vitro, and the involvement of biological clocks, i.e. ageing processes. These data, when available, should help us to understand better the nature of cancer and lead us to more effective methods of prevention and cure.Abbreviations AIDS acquired immunodeficiency syndrome - ALV avian leukosis virus - COFAL complement-fixation test for avian leukosis viruses - FeLV feline leukaemia virus - kb kilobases - L/S viruses leukosis/sarcoma viruses - MMTV mouse mammary tumour virus - MuLV mouse leukaemia virus - wt wild type     

Pathogenic mechanisms of caprine arthritis-encephalitis virus

Goats infected with caprine arthritis-encephalitis virus (CAEV) show chronic arthritis and cachexia, which are progressive in nature. The immunopathogenic mechanisms responsible for these progressive clinical symptoms have not been fully elucidated. Various haematological and immunological parameters were evaluated in experimentally-infected goats showing typical signs of CAEV-induced disease. Infected goats showed recurrent lymphocytosis that may be due to constant presentation of antigen by infected cells of a monocyte/macrophage lineage. The serum alkaline phosphatase and -glutamyl transferase concentrations were elevated in infected goats, a characteristic of hepatic and bone disorders. All other serum chemistry parameters were similar between infected and control goats. Importantly, the serum tumour necrosis factor- (TNF-) levels were higher in infected goats. The cachexia seen in infected goats may be at least partly due to altered metabolism as a result of prolonged elevation of serum TNF- levels. Depressed natural killer cell activity was observed in infected goats and may contribute towards the establishment of a persistent infection with CAEV.Abbreviations AIDS acquired immunodeficiency syndrome - CAEV caprine arthritis-encephalitis virus - GGT -glutamyl transferase - HBSS Hanks' balanced salt solution - HIV human immunodeficiency virus - NK natural killer - PBMC peripheral blood mononuclear cells - PCR polymerase chain reaction - SAP serum alkaline phosphatase - TNF tumour necrosis factor     

Neural control of gastro-intestinal motility; Events following receptor activation

The motility of the mammalian gastro-intestinal tract is regulated by a number of neuronal systems. The postganglionic, intramural parts of these systems are characterized by their neurotransmitters as cholinergic, adrenergic and purinergic nerves, respectively. The transmitter acetylcholine evokes contractions of the smooth muscle cell, whereas both noradrenalin and the transmitter from the purinergic nerves, presumably ATP, induce relaxations of smooth muscles. Agents and actions which influence the neurohumoral transmission and the mechanisms underlying the effects induced by the transmitters in smooth muscle cells are reviewed.     

The use of vitamin D metabolites and analogues for the prevention of milk fever in dairy cattle

During the past decade it has been discovered that vitamin D₃ (cholecalciferol) is converted into 25-hydroxycholecalciferol in the liver and that this compound in converted in the kidney into 1, 25-dihydroxycholecalciferol. These metabolites and particularly 1, 25-dihydroxycholecalciferol, rather than vitamin D itself, have powerful effects on calcium metabolism, stimulating the absorption of calcium from the gastrointestinal tract and the resorption of calcium from bone. A synthetic analogue of these metabolites, 1-hydroxycholecalciferol, is rapidly converted in the liver into 1, 25-dihycroxycholecalciferol. Thus the two metabolites and the synthetic analogue may be valuable for the prevention on treatment of milk fever.The three compounds, when administered in doses ranging from 0.5 to 32g/kg bodyweight increase the concentrations of calcium and phosphorus in the blood plasma of cattle more quickly than much larger doses of vitamin D₃. Their principal effect is to stimulate the absorption of calcium from the gastrointestinal tract. At the same time they decrease the plasma concentration of magnesium slightly. Trials of 25-hydroxycholecalciferol and 1-hydroxycholecalciferol in the prevention of milk fever have shown promising results.

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Kurzfassung Im vergangenen Jahrzehnt hat man festgestellt, dass das Vitamin D₃ (Cholecalciferol) in der Leber in 25-Hydroxycholecalciferol umgewandelt wird und die Nieren diese Verbindung wiederum in 1, 25-Dihydroxycholecalciferol umbilden. Mehr noch als Vitamin D selbst zeigen diese Metaboliten und hier insbesondere das 1, 25-Dihydroxychlecalciferol umfangreiche Auswirkungen auf den Kalziummetabolismus, indem sie die Kalziumabsorption aus dem Magen-Darmtrakt und die Kalziumresorption der Knochen anregen. Ein synthetischer Analogstoff zu diesen Metaboliten, das 1- Hydroxycholecalciferol, wird in der Leber rasch in 1, 25-Dihydroxycholecalciferol umgewandelt. Die beiden Metaboliten und der synthetische Analogwirkstoff könnten daher für die Milchfieberprophylaxe bzw-therapie von Nutzen sein.Werden die drei Verbindungen in Dosen von 0,5 bis 32g/kg Körpergewicht verabreicht, so erhöht sich die Kalzium-und Phosphorkonzentration im Blutplasma der Kühe schneller als bei bedeutend höheren Dosen von Vitamin D₃. Ihre Hauptwirkung liegt in der Anregung der Kalzium-absorption aus dem Magen-Darmtrakt. Gleichzeitig bauen sie jedoch auch in geringfügigem masse die Magnesiumkonzentration im Plasma ab. Versuche mit 25-Hydroxycholecalciferol und 1-Hydroxycholecalciferol haben bei der Milchfieberprophylaxe vielversprechende Ergebnisse gezeigt.

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Resume Au cours de la dernière décennie, on a découvert que la vitamine D₃ (cholécalciférol) se transformait en 25-hydroxycholécalciférol dans le foie et que ce composé se transformait en 1, 25-dihydroxy-cholécalciférol dans le rein. Ces métabolites, et en particulier le 1, 25-dihydroxycholécalciférol, ont, plus que la vitamine D elle-même, des effets puissants sur le métabolisme du calcium: ils stimulent l'absorption du calcium de l'appareil gastrointestinal et la résorption du calcium des os. Une substance homologue synthétique de cés metabolites, le 1-hydroxycholécalciférol, se transforme rapidement en 1, 25-dihydroxycholécalciférol dans le foie. Les deux métabolites et la substance homologue synthétique peuvent donc s'avérer précieux dans la prévention ou le traitement de la fièvre laiteuse.Administrés en doses allant de 0,5 à 32g/kg de poids corporel, ces trois composés augmentent les concentrations de calcium et de phosphore dans le plasma sanguin du bétail plus rapidement que des doses beaucoup plus fortes de vitamine D₃. Ils ont pour principal effet de stimuler l'absorption du calcium de l'appareil gastro-intestinal. Simultanément, ils réduisent légèrement la concentration de magnésium dans le plasma. Les essais d'utilisation du 25-hydroxycholécalciférol et du 1-hydroxycholécalciférol pour la prévention de la fièvre laiteuse ont donné des résultats prometteurs.

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Riassunto Nel corso dell'ultimo decennio si è scoperto che la vitamina D₃ (colecalciferolo) viene trasformata nel fegato in 25-idrossicolecalciferolo, il quale, a sua volta, si trasforma nel rene in 1, 25-diidrossicolecalciferolo. Detti metaboliti, ed in specie l'1, 25-diidrossicolecalciferolo., più che la stessa vitamina D, hanno potenti effetti sul metabolismo del calcio, poichè ne stimolano l'assorbimento da parte dell' apparato digerente e l'anabolizzazione da parte delle ossa. Un composto sintetico analogo di questi metobiliti, l'1, idrossicolecalciferolo, viene rapidamente trasformato nel fegato in 1, 25-diidrossicolecalciferolo. Perciò i due metaboliti e il composto sintetico analogo possono essere utili per la profilassi e la cura della febbre da latte.I tre composti, se somministrati in dosi da 0.5 a 32g/kg peso corporeo, aumentano la concentrazione del calcio e del fosforo nel plasma sanguigno del bestiame più rapidamente di dosi molto maggiori di vitamina D₃. Il loro effetto principale è quello di stimolare l'assorbimento del calcio da parte dell'apparato digerente. Contemporaneamente, essi riducono leggermente la concentrazione di magnesio nel plasma. Esperimenti con il 25-idrossicolecalciferolo nella profilassi della febbre da latte hanno dato risultati promettenti.

     

Food intake and rumen motility in dwarf goats. Effects of atipamezole on the inhibitory effects induced by detomidine,medetomidine and romifidine

The effects of some ₂-adrenoceptor agonists and of the ₂-adrenoceptor antagonist atipamezole on food intake and ruminal contractions were studied in dwarf goats. Detomidine, 0.2 µg/kg per min for 10 min, failed to modify food intake during either the first or second observation period (0–30 min and 180–210 min after drug infusion, respectively). Given at a higher dose rate (0.4 µg/kg per min for 10 min), the drug inhibited food consumption during the first observation period, but stimulated food intake during the second period. A similar pattern was observed after IV infusion with medetomidine (0.2 µg/kg per min for 10 min), romifidine (0.4 µg/kg per min for 10 min) or xylazine (1 µg/kg per min for 10 min). The ₂-antagonist atipamezole (2 µg/kg per min for 10 min) failed to modify food intake during either the first or second observation period. After treatment with atipamezole, the effects of ₂-agonists on feeding behaviour were completely antagonized.The ₂-agonists administered at similar dose rates to those used in the food intake experiments induced bradycardia, decreases in body temperature and inhibition of ruminal contractions. The inhibition of ruminal contractions induced by romifidine was partly antagonized by atipamezole pre-treatment. These findings demonstrate that the ₂-agonist-induced changes in ruminal contractions do not simply cause changes in feeding behaviour. The drop in body temperature induced by ₂-agonists was prevented by atipamezole pre-treatment, whereas the induced bradycardia was not modified by this ₂-antagonist.Abbreviations IV intravenous - SEM standard error of the mean     

Pharmacokinetics and distribution of sulphadimidine in plasma,milk and uterine fluid of female buffaloes

The pharmacokinetics of sulphadimidine after a single dose (200 mg/kg i.v.) was studied in five healthy lactating buffaloes. The study revealed that the drug attained its peak concentration of 314.0±13.0, 242.4±3.0 and 100.2±2.5 g/ml at 15 min, 30 min and 12 h in plasma, milk and uterine fluid, respectively. The pharmacokinetic parameters calculated by a 2-compartment open model gave values for t₁, t₁ and vd_area of 2.10±0.36 h, 12.36±0.57 h and 1.23±0.07 L/Kg, respectively. A high vd_area as well as a value of 0.74±0.08 for K₁₂:K₂₁- (tissue Plasma) indicates better penetration of the drug into the different body fluids and tissues, which is further supported by a high concentration obtained in milk and uterine fluid. The therapeutic concentration (50 g/ml) was maintained for around 24 h in plasma and milk and 12 h in uterine fluid. The results suggest that, apart from its use in systemic infections, the drug can be effectively used by the i.v. route in uterine and mammary gland infections. The dosages for maintaining concentration of 50 g/ml, 100 g/ml and 150 g/ml at convenient dosage intervals of 12 and 24 h were also determined.     

The influence of clenbuterol on prostaglandin F2α-induced dyspnoea in calves

Pulmonary function tests were performed in six healthy calves. Prostaglandin F₂ causes severe narrowing of both upper and lower airways (total lung resistance increased, dynamic compliance decreased). Clenbuterol administered intravenously fifteen minutes prior to prostaglandin F₂ aerosol, and in increasing doses (0, 0.4, 0.8, 1.2 g/kg), on days 1, 2, 4 and 6 of the experiment, effectively but not entirely suppressed these responses.These data indicate that -adrenergic receptors are present in the bovine airways and that the use of clenbuterol (0.8 g/kg) may be effective in treating clinical respiratory disease such as bronchopneumonia in calves.     

In vitro response to noradrenaline of small intestine taken from normal and grass sickness-affected horses

Small intestine was taken from the caudal flexure of the duodenum and the terminal ileum proximal to the ileocaecal fold of 25 horses, 9 with acute grass sickness (AGS), 12 with subacute grass sickness (SAGS) and 12 with chronic grass sickness (CGS). The motility in the samples was measured isometrically either within 1 h of death or after storage for 24 h at 4°C.In control tissue, noradrenaline produced contractions of muscle strips which did not involve a muscarinic cholinergic mechanism and which were unaffected by the 1 antagonist prazosin but were blocked by the 2 antagonist yohimbine. Pretreatment with the antagonist phentolamine prevented the contractile response to noradrenaline and the background contractions either continued at a reduced rate and amplitude or were abolished after a few minutes. Thus, following blockade, noradrenaline reduced the background contraction rate by an effect on inhibitory adrenoceptors. The rate of background contractions in duodenal preparations was significantly greater than that in control ileal preparations.Although cold storage for 24 h caused a reduction in the background contraction rates of the control preparations, there was no effect on the contractile responses to noradrenaline, the associated pharmacology being similar to that of fresh tissue. This suggests that noradrenaline-evoked contraction was not dependent on enteric neural elements.The response to noradrenaline by grass sickness-affected tissue was generally similar to that of tissue from control horses, with an immediate contraction which was 2 sensitive. The contractile response to noradrenaline after propranolol was significantly reduced in the CGS group and there were significant differences between the AGS, CGS and control groups. There was a significant difference between the ileal preparations from the control and SAGS groups in their response to noradrenaline following pretreatment with propranolol.     

Haemophilus influenzae and the β-adrenergic system: A review

Haemophilus influenzae is a bacterium that often can be isolated from the deeper respiratory airways of patients with chronic asthmatic bronchitis. In the present study the effects ofH. influenzae vaccination on guinea pig pulmonary -adrenoceptor number and function (in vitro and in vivo) have been evaluated. Functioning of -adrenoceptors is determined by measuring the -mimetic effect of isoprenaline on the inhibition of anaphylactic mediator release and isolated tracheal strip relaxation. The number of -adrenoceptor binding sites was measured by means of a³H-dihydroalprenolol binding assay.Also the mechanism of action underlying the changes in -adrenoceptor functioning was evaluated. Furthermore, it was established that the effect on the -adrenoceptor system was not specific forH. influenzae and that other respiratory pathogens were also biologically active in this respect.     

Safety of the attenuated anticoccidial vaccine ‘Paracox’ in broiler chickens isolated from extraneous coccidial infection

A trial was carried out in 1-day-old broiler chicks raised for 54 days in floorpens under simulated commercial conditions, but isolated from all extraneous virulent coccidial infections, to demonstrate the safety of Paracox attenuated vaccine administered at the recommended dose when chicks were 7 days old. The vaccine did not adversely affect the water consumption, faecal moisture or litter condition of the broilers. Recycling of the attenuated coccidia occurred in vaccinated birds, oocysts being present in the litter between 5 and 33 days after vaccination; a single peak of oocysts was detectable 5 or 12 days after vaccination. Unvaccinated medicated control birds did not produce oocysts, indicating freedom from both between-pen contamination by the vaccine and invasion of the chicken-house by extraneous coccidial infection. A small proportion (4%) of vaccinated birds had mild coccidial lesions when sampled at 26, 33 or 40 days after vaccination. Despite this, the vaccinated birds performed better than control (unvaccinated, nicarbazin-treated) birds and there was no post-vaccinal check in their weight gain. Their mean finishing weight was 10.4% greater, their food conversion ratio 7.2% lower and their mortality 44.4% lower than the unvaccinated control birds, reflecting the safety of Paracox vaccine.Abbreviation FCR food conversion ratio