Agent In Cattle Research Articles

MRI of Creutzfeldt–Jakob Disease: Imaging Features and Recommended MRI Protocol

Creutzfeldt–Jakob Disease (CJD) is a rare, progressive and invariably fatal neurodegenerative disease characterized by specific histopathological features. Of the four subtypes of CJD described, the commonest is sporadic CJD (sCJD). More recently, a new clinically distinct form of the disease affecting younger patients, known as variant CJD (vCJD), has been identified, and this has been causally linked to the bovine spongiform encephalopathy (BSE) agent in cattle. Characteristic appearances on magnetic resonance imaging (MRI) have been identified in several forms of CJD; sCJD may be associated with high signal changes in the putamen and caudate head and vCJD is usually associated with hyperintensity of the pulvinar (posterior nuclei) of the thalamus. These appearances and other imaging features are described in this article. Using appropriate clinical and radiological criteria and tailored imaging protocols, MRI plays an important part in the in vivodiagnosis of this disease. Collie, D. A. et al. (2001). Clinical Radiology56, 726–739.

Screening for anabolic steroids and related compounds in illegal cocktails by liquid chromatography/time-of-flight mass spectrometry and liquid chromatography/quadrupole time-of-flight tandem mass spectrometry with accurate mass measurement.

Findings of illegal hormone preparations such as syringes, bottles, cocktails, and so on, are an important information source for the nature of the current abuse of anabolic steroids and related compounds as growth-promoting agents in cattle. A new screening method for steroids in cocktails is presented based on liquid chromatography (LC) with diode-array UV-absorbance detection and electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS). Accurate mass measurements were performed at a mass resolution of 4000 using continuous introduction of a lock mass through a second (electro)sprayer. Similar experiments were carried out using dual-sprayer quadrupole time-of-flight mass spectrometry (ESI-QTOFMS/MS) at a mass resolution of 10 000 with data-dependent MS/MS acquisition; i.e. beyond an intensity threshold for the [M + H](+) ions, MS/MS spectra were automatically acquired at three different collision energies. Elemental compositions were calculated for precursor and product ions and it is shown that the combined information from LC retention behavior, UV spectra, elemental compositions, and accurate mass MS/MS spectra yield a fast impression of the steroids present in the complex mixture. Using a new software tool for structure elucidation of MS/MS spectra, an additional non-steroidal additive was identified as well.

The control of VTEC in the animal reservoir

A great diversity of VTECs exist but only in the case of Escherichia coli O157:H7, a common human foodborne pathogen, has sufficient research been done to allow generalizations about the ecology. The key features are as follows: lack of host specificity such that indistinguishable isolates can be found in a variety of species; near-ubiquitous distribution in cattle (and perhaps other ruminant) farms; transient residence in the gastrointestinal flora of individual animals that is not associated with clinical disease; temporal clustering at the population level such that most fecal shedding is confined to sharp bursts in a high percentage of animals separated by much longer periods of very low prevalence; a higher prevalence in young animals in comparison to older ones; a higher prevalence in animals with floral disturbance such as that caused by transit, feed changes or antimicrobial dosing; and a markedly higher prevalence during warm months. Molecular epidemiological studies of E. coli O157:H7 have demonstrated that subtypes of the organism can persist on cattle farms for years, thus supporting a conclusion that cattle farms represent a reservoir. Yet on such farms, common subtypes are often found in environmental niches and in other species of animals; thus, it is not completely clear that cattle themselves are the reservoir. New subtypes are periodically observed on particular farms, and indistinguishable subtypes can be found on farms that are separated by hundreds of kilometers even in the absence of any obvious animal movements between them. The number of subtypes found on a farm does not appear to be qualitatively correlated with cattle movements (e.g., purchases) into the farm. Commercial feeds are sometimes contaminated with E. coli O157:H7, and it seems likely that feeds represent an important route of dissemination for this agent and other VTEC. Mixed feeds collected from feeding troughs are commonly positive for E. coli O157:H7, as are cattle watering troughs, and feed and water likely represent the most common means of infection. Environmental replication in feeds and in sediments of watering troughs occurs and may account for the higher level of fecal shedding in the warm months. Since E. coli O157:H7 has been found to persist and remain infective for at least 6 months in water trough sediments, this may be an important environmental niche where the organism survives during periods when it cannot be detected in cattle, especially during cold months. Traditional means of controlling infectious agents, such as eradication or test and removal of carrier animals, do not appear to be feasible for VTECs. Nevertheless, certain farm management practices—especially those related to maintenance and multiplication of the agent in feed and water—may provide practical means to substantially reduce the prevalence of these agents in cattle on farms and in those arriving at slaughter plants.

Antiviral and antiluteolytic activity of recombinant bovine IFN-omega1 obtained from Pichia pastoris.

The gene coding for bovine interferon-omega1 (BoIFN-omega1) was recently cloned and expressed at high levels in the yeast Pichia pastoris. The recombinant BoIFN-omega1 protein shows antiviral activity in different cell lines and has an antiluteolytic effect in cyclic ewes. In this article, we describe a method for purification of BoIFN-omega1 expressed in the methylotrophic yeast P. pastoris and characterization of its activity in vivo. The recombinant protein secreted to the culture medium had low activity because of self-aggregation. BoIFN-omega1 was solubilized using urea and desalting and finally purified by ion exchange chromatography on Q-Sepharose Fast Flow. The yield of purified product was approximately 300 mg/L of fermentation culture, with a specific antiviral activity of 10(8) IU/mg. Its purity was at least 80%. The biologic characterization of purified BoIFN-omega1 was determined by induction of an antiviral state on ewes challenged with 100 lethal doses (LD) of Aujeszky virus and by the extension of the corpus luteum life span and interestrous interval in cyclic cows. Ewes treated with 2 x 106 IU/kg BoIFN-omega1 were protected from Aujeszky virus infection. In cows receiving an intrauterine infusion of 1 mg BoIFN-omega1, equally distributed between the two uterine horns, twice daily from day 14 to day 22 of the experimental estrous cycle, the lifespan of the corpus luteum (25 vs. 19 days) and the interestrous intervals (26 vs. 21 days) were extended when compared with a control group (p < 0.05). We show that recombinant BoIFN-omega1 purified from P. pastoris has high antiviral activity and is an effective antiluteolytic agent in cattle.

Second passage of a US scrapie agent in cattle

Scrapie and bovine spongiform encephalopathy are similar chronic neurodegenerative diseases of sheep and cattle. An earlier study showed that, on first passage in cattle, a US scrapie agent caused an encephalopathy that was distinct from bovine spongiform encephalopathy (BSE). The present report describes a second passage in cattle, carried out because diseases caused by the spongiform encephalopathy agents often change in character with additional passages in abnormal hosts. For this work, young calves were inoculated intracerebrally with a pooled suspension of brain from cattle that had died of encephalopathy after experimental inoculation with brain from scrapie-affected sheep. The second passage disease was essentially identical with the first passage disease, as judged by clinical signs, histopathological findings and distribution of "prion protein scrapie" (PrPsc). This represents additional evidence to suggest that the US sheep scrapie agent tested is incapable of causing BSE in cattle.

The role of botfly myiasis due to Dermatobia hominis L.Jr. (Diptera:Cuterebridae) as a predisposing factor to New World screwworm myiasis (Cochliomyia hominivorax coquerel) (Diptera:Calliphoridae).

In the tropics, the botfly Dermatobia hominis and the NWS Cochliomyia hominivorax are the most important myiasis agents in cattle. It is frequently reported that furuncular lesions due to D. hominis are a predisposing cause for screwworm myiasis. Our results pointed out that only 5.2 to 7.4% of C. hominivorax gravid females oviposited in the offered furuncular lesions. Of 3242 eggs layed on botfly lesions (BFL), only 82 (2.5%) developed to second instar and died. In the flies tested, the furuncular lesions due to Dermatobia were used as food supply in 81.3% of the cases. In our opinion, the role of pH, the microflora associated with BFL, and the foruncular structure were the reasons for this lack of attraction. BFL do not serve as a predisposing factor for screwworm myiasis in the tropics.

Synovex® H as a prenatal androgenizing agent in beef cattle: Effects on the implanted pregnant heifer

A study was conducted to evaluate the effectiveness of Synovex® H as an agent for prenatal androgenization in beef cattle. Thirty Charolais-cross heifers, exposed to a fertile bull during a 55-d spring breeding season, were randomly assigned to a control group or implanted with three times the normal dose of Synovex® H between days 20 and 75 of gestation. Serum concentrations of testosterone, estradiol, and progesterone, calving rate, and growth performance were determined in the pregnant heifers. Testosterone levels were greater (P &lt; 0.001) in treated heifers than in control heifers. Synovex® H treatment had no affect on estradiol levels. Progesterone levels were lowered (P &lt; 0.05) in treated heifers. Synovex® H treatment decreased (P &lt; 0.05) calving rate and birth weight of calves born to treated heifers. Calving ease scores were not affected by Synovex® H treatment. Weight was not affected; however, average daily gain was improved 7% by Synovex® H treatment (0.88 vs. 0.82 ± 0.04 kg d−1, treated and control heifers, respectively). These results are interpreted to suggest that Synovex® H is not an appropriate androgenizing agent for cattle due to adverse effects on progesterone concentrations during pregnancy and on calving rate. Key words: Cattle, prenatal androgenization, Synovex® H, pregnancy, hormones

HCV genotype in interferon non-responders treated for over one year . Central Blood Bank and West Penn Hospital, Pittsburgh, PA

Waddlia chondrophila is a strict intracellular microorganism belonging to the order Chlamydiales that has been isolated twice from aborted bovine fetuses, once in USA and once in Germany. This bacterium is now considered as an abortigenic agent in cattle. However, no information is available regarding the presence of this bacterium in Africa. Given the low sensitivity of cell culture to recover such an obligate intracellular bacterium, molecular-based diagnostic approaches are warranted. This report describes the development of a quantitative SYBR Green real-time PCR assay targeting the recA gene of W. chondrophila. Analytical sensitivity was 10 copies of control plasmid DNA per reaction. No cross-amplification was observed when testing pathogens that can cause abortion in cattle. The PCR exhibited a good intra-run and inter-run reproducibility. This real-time PCR was then applied to 150 vaginal swabs taken from Tunisian cows that have aborted. Twelve samples revealed to be Waddlia positive, suggesting a possible role of this bacterium in this setting. This new real-time PCR assay represents a diagnostic tool that may be used to further study the prevalence of Waddlia infection.

Extension of Corpus Luteum Lifespan and Reduction of Uterine Secretion of Prostaglandin F2α of Cows in Response to Recombinant Interferon-τ

Two experiments tested the effect of recombinant ovine and bovine interferon-τ on corpus luteum lifespan, interestrous interval, and oxytocin-induced uterine secretion of prostaglandin F2α. Cows received intrauterine injections of 100μg of recombinant ovine interferon-τ plus 1.4mg of BSA or of 1.5mg of BSA alone in Experiment 1 and 200μg of recombinant bovine interferon-τ plus 1.3mg of BSA or 1.5mg of BSA alone in Experiment 2. Twice daily injections (0700 and 1900h) were split evenly between the uterine horns from d 14 to 24 of the experimental estrous cycle via an AI pipette in Experiment 1 and via intrauterine catheters in Experiment 2. On d 17, cows were injected with 100 IU of oxytocin, and plasma was collected for analysis of 13,14-dihydro-15-keto-prostaglandinF2α. Recombinant ovine interferon-τ extended the lifespan of the corpus luteum (27.5 vs. 19.2 d) and interestrous interval (30.5 vs. 20.6 d) and abolished the oxytocin-induced increase in 13,14-dihydro-15-keto-prostaglandinF2α, which peaked at 30min for the BSA control group (210.8 pg/ml). Recombinant bovine interferon-τ also extended the lifespan of the corpus luteum (29.0 vs. 21.4 d) and interestrous interval (31.5 vs. 22.6 d) and abolished the oxytocin-induced increase in 13,14-dihydro-15-keto-prostaglandin F2α, which peaked at 30min for the BSA control group (205.6 pg/ml). In conclusion, recombinant ovine interferon-τ and recombinant bovine interferon-τ were effective antiluteolytic agents in cattle.

Injectable Anesthetic Agents and Techniques in Ruminants and Swine

This article reviews the use of injectable anesthetic agents in cattle, sheep, goats, and swine. Emphasis is placed on short-term general anesthesia. Methods and drugs employed for continuous intravenous infusion are discussed. Capture drugs for fetal animals are briefly reviewed, as is electroimmobilization.

Comparative studies on cardiovascular, respiratory and gastrointestinal effects of the sedatives R 51163 and xylazine in cattle

AbstractR 51163 and xylazine are rougly equipotent sedative agents in cattle. The effects of i.v. injections of R 51163 and xylazine on acid‐base status, arterial and venous blood gas tension, cardiovascular parameters, and rumen motility were compared in adult healthy cattle. With R 51163 heart rate increased and respiratory rate decreased. Xylazine decreased both heart rate and respiratory rate. Both drugs caused minor changes in arterial and venous blood parameters and blood pressure. The overall cardiovascular and respiratory changes produced by either drug remained within physioloical limits of normal awake cattle. After injection of R 51163, rurnination was inhibited but recurred within 45 min. Antegrade and retrograde contractions were slightly inhibited. Xylazine completely blocked rumination for at least 2 hr. Antegrade contractions were absent for 40 min. Antegrade and retrograde contractions were decreased during both the first and second 60‐min follow‐up period. Both R 51163 and xylazine produced modest cardiovascular and respiratory effects. Xylazine, when compared to R 51163, produced a profound depression of rumen motility. These effects have limited consequences in normal fasted cattle, but should be taken into account in diseased non‐fasted cattle with impaired cardiovascular functions.

Resorcylic acid lactone as an anabolic agent in cattle.

This paper discusses the use of resorcylic acid lactone as an anabolic agent in cattle. When given to finishing steers it increases daily gain by 10–18% and final carcass weight by 6–10 kg. When given to finishing steers in conjunction with trenbolone acetate, there is an additive response in terms of growth rate and carcass weight. The final carcass weights were 310±2.1, 319±2.0, 316±2.0 and 328±2.0 for unimplanted steers, or steers implanted with resorcylic acid lactone or trenbolone acetate or a combination of both compounds respectively. Responses in finishing steers in spring at pasture were similar to responses obtained in winter. In male calves, average liveweights at the end of a 134-day experimental period were 123, 142 and 140 kg (SE ± 5.4 kg) respectively for control calves or calves given resorcylic acid lactone or a combination of resorcylic acid lactone and trenbolone acetate. After a further 134 days grazing together these calves weighed 271, 294 and 297 kg (SE ± 7.9 kg) respectively, indicating that the extra gain was retained once the implants ceased to be effective. No significant effect on daily gain or carcass weight of heifers was obtained in our trials with resorcylic acid lactone. Results from feed efficiency trial indicated resorcylic acid lactone significantly increased feed efficiency. Therefore, resorcylic acid is an effective growth promoter in male castrate cattle.

Ivermectin as an Antiparasitic Agent in Cattle

This paper summarizes the efficacy and safety evaluation of ivermectin given as a single subcutaneous injection for the control of a wide range of nematode and arthropod parasites of cattle. lvermectin for the treatment and control of parasites in cattle was evaluated in 56 efficacy studies and 181 field trials prior to market introduction. A total of 8,205 cattle were involved, of which 5,094 received ivermectin at 200 mcg/ kg or more, the remainder serving as contemporary controls. It is concluded from the data that ivermectin is safe forcattle when used under practical husbandry conditions at the recommended use level. Subsequent to the compiling of the data for registration submission and prior to large scale commercial use of ivermectin injection, a total of 20,838 cattle in 18 countries were successfully involved in the research and developmenteffort.

Metabolism of endogenous and exogenous anabolic agents in cattle.

The endogenous anabolic agents, estradiol-17 beta, progesterone and testosterone are steroids that are quickly metabolized by the liver and are not very active when administered orally. Estradiol-17 beta is excreted by the bovine in bile as free estradiol-17 alpha, and by swine, in urine, as glucuronides and sulfates. In ruminants, the primary metabolite of progesterone is pregnandiol and that of testosterone is epitestosterone. In horses, the metabolites of these compounds are primarily 17 ketosteroids. Esters of the endogenous anabolic agents are rapidly hydrolyzed and the nonesterified forms follow the same biotransformation pathways as the natural compounds biosynthesized by the animal. The exogenous anabolic agents, such as trenbolone acetate, zeranol and diethylstilbestrol, may be active by the oral route and are less readily metabolized in the liver than the endogenous anabolics. Their metabolic pathways may be complex and lead to excreted forms after glucuronide conjugation. With respect to biochemical mechanism of action, it can be assumed that the anabolics act like all steroids by way of intracellular receptors. Biotransformations could lead to more reactive molecules that may bind themselves to normal constituents of the organism. Bound metabolites are generally formed later than free metabolites, and are considered less toxic with a lower level of bioavailability.

Field investigation of the effect of 5 mg PGF2α given intravenously to cycling beef cows and heifers

Prostaglandin F2α (PGF2α) has been proven to be an effective luteolytic agent in cattle when administered after day 5 of the cycle. While the recommended dose of PGF2α in cattle has been established as 25 mg IM, there have been field reports that a dose as low as 5 mg PGF2α IV was effective in obtaining luteolysis. It has been documented that 5 mg PGF2α IM was luteolytic in hysterectomized heifers and a dose of .5 mg PGF2α IV has caused estrus and evacuation of purulent material in cows with pyometra.&#x0D; The purpose of this field trial was to determine the efficacy of 5 mg PGF2α IV in causing luteolysis and estrus in a group of cycling beef cows.

Attenuated strains of the virus of foot-and-mouth disease. Studies in small animals with strains of common origin modified by different methods

By passage in unweaned mice, in weaned mice (mo strain), or in chick embryos, a cattle strain of foot-and-mouth disease — Strain119, Type A —was attenuated to the stage when there was virtual extinction of the ability of the virus to produce vesicular lesions in steers. These three strains of common origin also show a marked reduction in epitheliotropism for the guinea-pig but their myotropism for the guinea-pig and adult mouse varies widely and tests using these small animals can readily differentiate between them. Such tests may assist in detecting strains which are immunogenic for cattle. Themo strain was the most myotropic for these small animals and this strain has proved to be a good immunising agent for cattle when inoculated intramuscularly.