ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00667.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The affinity of doxycycline for crystalline plasma albumin fraction V, originating from sheep, dogs, cats, cows, pigs and humans, was evaluated by means of double‐reciprocal and Scatchard plots. Mathematical modelling and weighted least‐squares non‐linear regression analysis of each Scatchard plot identified one binding component characterized by one high affinity binding site, and a second component attributed to non‐specific binding to albumin. Association constants for this binding site ranged from 38 471 ± 13 369 (SEM) l/mol for the interaction of doxycycline with ovine albumin to 6405 ± 2375 l/mol for the interaction of doxycycline with human albumin. Statistical evaluation of the results suggested slight species‐related differences in the values of association constants. Diphenylhydantoin, phenobarbital or carbamazepine did not displace doxycycline from binding sites on bov

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00668.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

In five conscious adult ewes at rest, chronically implanted with electrodes in the musculature of the omasal wall, intravenous (i.v.) infusion for 30 min of α1‐ or α2‐adrenergic receptor blockers, prazosin (20 μg/kg/min) and yohimbine (30 μg/kg/min), respectively, had no significant effects on omasal myoelectrical activity. The i.v. administration for 15 min of α1‐ or α2‐agonists phenylephrine (4 μg/kg/min) or naphazoline (2.5 μg/kg/min), respectively, increased the frequency and the amplitude of groups of myoelectrical discharges of omasum, as well as the duration of its activity. Pretreatment of animals with prazosin blocked the responses to phenylephrine. Yohimbine prevented the effects of naphazoline dose‐dependently. It is suggested that both α1‐ and α2‐adreno‐receptors are involved in regulation of the sheep's omasal notility. This regulation did not seem to be a simple consequence of the changes

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00669.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The minimal inhibitory concentrations (MIC) of five tetracyclines and ten other antimicrobial agents were determined for four porcine bacterial respiratory tract pathogens by the agar dilution method. For the following oxytetracycline‐susceptible strains, theMIC50ranges of the tetracyclines were:P. multocida(n= 17) 0.25–0.5 μg/ml;B. bronchiseptica(n= 20) 0.25–1.0 μg/ml;H. pleuropneumoniae(n= 20) 0.25–0.5 μg/ml;S. suisType 2 (n= 20) 0.06–0.25 μg/ml. For 19 oxytetracycline‐resistantP. multocidastrains theMIC50of the tetracyclines varied from 64 μg/ml for oxytetracycline to 0.5 μg/ml for minocycline. Strikingly, minocycline showed no cross‐resistance with oxytetracycline, tetracycline, chlortetracycline and doxycycline inP. multocidaand inH. pleuropneumoniae.Moreover, in susceptible strains minocycline showed the highestin vitroactivity followed by doxycycline. LowMIC50values were observed for chloramphenicol, ampkillin, flumequine, ofloxacin and ciprofloxacin againstP. multocidaandH. pleuropneumoniae. B. bronchisepticawas moderately susceptible or resistant to these compounds. As expected tiamulin, lindomycin, tylosin and spiramycin were not active againstH. pleuropneumoniae.Except for flumequine, theMIC50values of nine antimicrobial agents were low forS. suisType 2. Six strains of this species showed resistance to the macrol

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00670.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

To determine whether cholinesterase inhibition by an organophosphate would influence atracurium's neuromuscular blockade, six horses were anesthetized and paralyzed with atracurium (total of five injections per horse) on experimental Day 1, then were given trichlorfon (64 mg/kg per os) 6 days later. On Day 7, horses were anesthetized and paralyzed in the same manner as on experimental Day 1. Blood was taken to measure serum cholinesterase activity prior to anesthesia on Days 1 and 7. No significant difference was noted in atracurium's neuromuscular blocking activity between the 2 experimental days (P<0.05), despite Day 7 cholinesterase activity that was 16% of pre‐trichlorfon values. For atracurium Injections 1 and 2–5, 85 and 43 μg/kg of atracurium, respectively, were required to produce a 95–99% reduction in hoof twitch. The time from injection to maximum twitch reduction was approximately 9 min after Injection 1 and 5 min after subsequent injections. Time from injection to maximum twitch reduction was significantly longer for Injection 1 than Injections 2–5 on both experimental days. The time from maximum twitch reduction until 10% recovery was approximately 8 min, with no significant difference between experimental days. The time for twitch recovery from 10 to 75% was approximately 17 min for all injections. Antagonism of atracurium with edrophonium caused the twitch height to return to pre‐atracurium strength in approximately 7 min. Edrophonium caused a significant increase in arterial blood pressure. Heart rate change was variable after edrophonium. Recovery to standing was uneventful for five of the six horses on Day 1, and for all six horses on Day 7. It was concluded that atracurium's neuromuscular blockade was not prolonged by trichlorfo

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00671.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The effects of jingsongling (JSL) and xylazine on heart rate (HR) and mean arterial pressure (MAP) were studied in five conscious male dogs. An i.v. injection of xylazine (1 mg/kg) caused a bradycardia, an initial hypertension, and a subsequent hypotension. An i.v. injection of JSL (1 mg/kg) caused a bradycardia and a 20‐min hypertension without a subsequent hypotension. Atropine sulfate (45 μg/kg, i.v.) increasedHRfor 30 min without changingMAP, and antagonized JSL‐induced bradycardia for at least 60 min. There was a subsequent rebound bradycardia. Atropine sulfate potentiated JSL‐induced hypertension in both magnitude and duration. Yohimbine (0.1 mg/kg, i.v.), an α2‐adrenoceptor antagonist, increasedHRandMAPfor 110 and 70 min, respectively. Yohimbine not only failed to potentiate but even reversed the pressor effect of JSL in a dose‐dependent manner. Yohimbine also caused a dose‐dependent reversal of JSL‐induced bradycardia. Tolazoline (5 mg/kg, i.v.), a nonselective α‐adrenoceptor antagonist, increasedMAPfor 20 min without changingHR.Tolazoline also reversed JSL‐induced hypertension and bradycardia. Prazosin (1 mg/kg), an α1‐adrenoceptor antagonist, decreasedMAPand increasedHRfor at least 110 min. Prazosin reversed JSL‐induced hypertension but failed to affect JSL‐induced bradycardia. These results indicated that: (1) JSL‐induced bradycardia and hypertension are mediated by α2‐adrenoceptors; (2) yohimbine and tolazoline may be useful in antagonizing these untoward reactions associated with JSL administration, whereas prazosin and atropine were not found

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00672.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A comparison of i.v., i.m. and s.c. administration erythromycin base in polyethylene glycol at 15 mg/kg and 30 mg/kg body weight was carried out in beef‐type calves of approximately 200 kg body weight. Additional evaluations were carried out with oral administration of erythromycin phosphate and erythromycin stearate. Absorption of erythromycin was very slow by both the i.m. and s.c. routes of administration with a Kabof 0.0135 min‐1and 0.0185 min‐1for i.m. and 0.0032 min‐1and 0.0074 min‐1for s.c. at 15 mg/kg and 30 mg/kg, respectively. The bioavailability (32–42%) and peak serum concentrations were much lower with s.c. than with i.m. (60–65%) administration. The disposition of erythromycin administered i.v. appeared to be representative of dose‐dependent kinetics rather than dose‐independent first‐order kinetics inasmuch as the elimination half‐time (t1/2B) increased from 174.5 ± 13 min for the 15 mg/kg dosage to 239 ± 10.8 min with 30 mg/kg dosage. An acute apparent cardiovascular effect accompanied i.v. administration of erythromycin at 30 mg/kg dosage but not at 15 mg/kg. Severe diarrhea followed oral administration of either erythromycin phosphate o

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00673.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Avilamycin, an oligosaccharide antibiotic with growth‐promoting properties in pigs, has proved to be effective in controlling stress‐induced post‐weaning diarrhoea in piglets, caused mainly byEscherichia coli.The present study includes two trials, in which 400 newly‐weaned piglets were used (200/trial). The following five different treatments were tested; 0, 40 and 80 p.p.m. avilamycin, 50 p.p.m. olaquindox and 100 p.p.m. apramycin. In each trial there were four pens (each with five females and five males) per treatment. Avilamycin when given at 80 p.p.m. reduced average daily diarrhoea score (ADDS) and mortality, and improved liveweight gain and feed conversion ratio (FCR), compared with the untreated controls, the 40 p.p.m. avilamycin and the 50 p.p.m. olaquindox (P<0.05) treatments. The overall performance of 40 p.p.m. avilamycin and 50 p.p.m. olaquindox was similar. The results indicate that avilamycin at the dose level of 80 p.p.m. in the starter feed can control post‐weaning diarrhoea of piglets and prevent loss of productivity. Nevertheless, the antibiotic apramycin, whose spectrum of activity is mainly against the Gram‐negative bacteria, given at the therapeutic level of 100 p.p.m., was more effective than any other experimental treatment (P<0.05), except forADDSandFCRwhich were not significantly different from that of avilamyc

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00674.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Doses of 0.005–1.0 mg of ACTH1–24given intravenously, intramuscularly or as an intramuscular depot injection caused increases in Cortisol concentrations within 15 min in the plasma of ewes. There was, however, considerable animal‐to‐animal variation in maximum concentrations achieved. A curvilinear dose‐response relationship to ACTH1–24was obtained which was similar for each route of administration when expressed in terms of maximum Cortisol concentrations. However, for a given dose, more prolonged release of Cortisol occurred after i.m. injection compared to i.v., with maximum concentrations occurring 6 h after the depot formulation injection. Five repeated daily doses of 1.0 mg depot ACTH1–24resulted in no diminution of Cortisol response indicating considerable synthesizing capacity of the adrenals in clinically normal ewes. Comparison of cortisol concentrations after an acute stressor (shearing) suggests that doses of ACTH1–24greater than 0.25 mg are excessive for simulation of stress‐induced

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00675.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The effect of flunixin meglumine on prostaglandin synthesis and metabolism was evaluated in the pigin vivo.It was found that the prostaglandin metabolite, 15‐ketodihydro‐PGF2α, was decreased in the peripheral circulation within 20 min of injection of the drug. In therapeutic doses in the pig the drug had no effect on the metabolism of PGF2α. Flunixin was compared with some other non‐steroidal anti‐inflammatory drugs in anin vitrotest system utilizing sheep vesicular gland microsomes. It was concluded that this drug is a potent inhibitor of prostaglandin

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00676.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY