Measurement of protein turnover in skeletal muscle strips

Isolated porcine and bovine muscle strips were incubated in Krebs Ringer bicarbonate buffer to determine in vitro protein synthesis (PS) and protein degradation (PD) rates to validate the in vitro system for use with livestock species. The addition of 5X plasma concentrations of amino acids to the medium stimulated PS 30%. Addition of 3.5 mM leucine to a leucine-deficient buffer supplemented with amino acids decreased PD 37% and stimulated PS 24%. The addition of .1 U/ml insulin reduced PD 28% and increased PS 30%. Protein degradation was elevated in longitudinally split rat soleus and extensor digitorum longus muscles compared to their contralateral intact muscles. Muscle strips must be removed within 15 min of exsanguination because PD rates become greatly elevated thereafter. ATP concentrations declined during incubation, but the addition of ATP or creatine had no effect on either PD or PS. Neither PD nor PS was affected by the addition of transferrin, fetuin, ascorbate, dexamethasone or indomethacin to the incubation medium. However, muscle strips were sensitive to the addition of triiodothyronine (T3), PD was increased up to 75% as T3 concentration was increased, and PS rates doubled compared to controls. Serum from mature barrows or gilts had no effect on protein turnover, but the addition of 10% and 15% serum from boars increased both PD and PS. With fasted pigs a continual decline in PS occurred over 5 d, whereas PD was elevated at 3 d and then declined to rates comparable to the fed state after 5 d. These data suggest that the in vitro system has application for assessing relative changes that occur in vivo following nutritional, physiological and endocrinological manipulation.     

Quantitative correlation of parasitological and serological techniques for the diagnosis of Trypanosoma congolense infection in cattle

A comparison was made between serological and parasitological techniques for the diagnosis of bovine trypanosomiasis in Zambia. Overall sero-prevalence rates as determined by IFAT and ELISA were respectively 2.7-fold and 2.9-fold greater then the percentage of samples found positive with the dark ground/phase contrast buffy coat technique (DG). The results obtained by the two serological techniques were found to be closely correlated (94.2%) agreement) and titres obtained by ELISA tended to be slightly higher than those obtained by IFAT. Linear regression analysis of the results obtained by the IFAT and DG techniques revealed a highly significant correlation. This finding would permit the use of only one of the techniques in an epidemiological survey and to extrapolate the results from the regression line.     

Prevalence of Giardia in the feces of pups

Fecal specimens were collected from 117 healthy pups (79 privately owned pups and 38 pups from an animal shelter) and analyzed for Giardia. Giardia cysts or trophozoites were found in 35.9% of the dog feces.     

Pathogenesis of Mycobacterium bovis infection in American bison

Eighteen 12-month-old bison were randomly placed in each of 3 groups (6 animals/group): group-1 bison were exposed to live Mycobacterium bovis, group-2 bison were inoculated with killed M bovis in oil, and group-3 bison were noninfected controls. Six, 6-month-old, tuberculin test-negative calves were placed (pen contact) with group-1 bison 30 days after exposure to M bovis. Tuberculin skin test responses (caudal fold and/or comparative cervical) were detected in all bison in groups 1 and 2 at 2, 4, 6, 10, and 12 months. Tuberculin skin test responses were observed in 2 of 6 calves at 9 and 11 months after pen contact with M bovis-exposed bison (group 1). Statistically significant lymphocyte blastogenic responses to M bovis purified protein derivative were detected in group-1 bison exposed to live M bovis at 2 months after exposure (P less than 0.025). Significant ELISA reactions were detected in sera of bison at 2 months after exposure to killed M bovis in oil (P less than 0.005) and in bison 2 months after exposure to live M bovis (P less than 0.01). Significant tuberculin skin responses, ELISA reactions, or lymphocyte blastogenic responses to M bovis purified protein derivative were not observed in the 6 control bison. Grossly visible tuberculous lesions were observed in lymph nodes and/or lung collected at necropsy in 4 of 6 bison at 12 months after exposure to live M bovis. Microscopic granulomas compatible with tuberculosis were detected in 5 of 6 bison; M bovis was isolated from tissues of each of the 6 bison.(ABSTRACT TRUNCATED AT 250 WORDS)     

Repletion of blood selenium concentrations in weaned beef calves

Eighty-three weaned beef calves severely deficient (less than 20 micrograms/L) in blood selenium (Se) were allotted by sex, weight and breed to one of six regimens of Se supplementation for 108 days to examine the efficacy of various Se supplementation programs and to monitor the repletion rate of blood Se concentrations. Cattle in treatment 1 received an IM injection of sodium selenite and an ad libitum feeding of 20 mg Se/kg salt-mineral mixture. Salt-mineral mixtures (treatments 2, 3, 4 and 5) were formulated to contain 20, 40, 80 and 160 mg Se/kg supplement, respectively, and were offered free-choice. Treatment 2 served as the selenium-treated control because 20 mg Se/kg supplement was the maximum permissible by FDA in commercial salt-mineral preparations at the time of this study. Cattle in treatment 6 received a salt-mineral supplement which contained no Se but dried brewers grain (434 micrograms Se/kg) was incorporated in the ration as an organic source of Se and fed at a rate of 1.1 kg/head/day. There was a within group time/treatment interaction (P less than 0.01) among all treatments as blood Se concentrations significantly increased over time. Final mean whole blood Se concentrations for treatments 1-6 were 87.8, 60.6, 95.1, 123.1, 154.2 and 91.4 micrograms/L, respectively. Treatments 1, 3, 4, 5 and 6 effectively increased and maintained whole blood Se concentrations at adequate levels (greater than 70 micrograms/L) by day 84. Treatment 2 (control) increased blood Se during the 108-day study, but blood Se concentrations never exceeded marginal levels (50-70 micrograms/L). Cattle consumed less salt-mineral supplement as the concentration of Na selenite increased from 20 to 160 mg Se/kg supplement.     

Progesterone receptors in feline mammary adenocarcinomas

Estradiol and progesterone receptors were measured in tumor cytosols from 3 intact and 4 neutered female cats with spontaneously occurring mammary adenocarcinomas. Serum from 2 of the intact cats which had been in estrus 4 and 4 to 6 weeks before tumor excision contained progesterone concentrations of 16.2 and 2.2 ng/ml, respectively; serum progesterone in the other cats was less than 2 ng/ml. Estradiol receptors were not detected in any cytosols. Progesterone receptors were detected in all of the cytosols, in concentrations ranging from 4.0 to 11.7 (mean = 7.2) fmol/mg of protein. Scatchard plot analysis of tumor cytosol from an 8th cat with mammary adenocarcinoma revealed presence of high affinity progesterone binding with a dissociation constant (Kd) of 3.47 nM. Tumor receptor content could not be correlated with stage of the estrous cycle nor with whether the cat was intact or neutered.     

Trials of an inactivated equid herpesvirus 1 vaccine: challenge with a subtype 1 virus

Vaccinated yearlings , two-year-old and in-foal pony mares with appropriate controls were exposed to aerosols of a subtype 1 virus one to two months after two or three vaccinations; all became infected. No obvious differences in the febrile responses, clinical signs and subsequent abortions were found between vaccinated and control mares. All vaccinated yearlings and two-year-old ponies developed a febrile respiratory disease but this was less severe than that suffered by the controls and the amounts and duration of virus shedding were reduced.     

The influence of the oestrous cycle on the intravenous glucose tolerance test in the bitch

The possibility that endogenous oestrogen and progesterone affect carbohydrate tolerance in the female dog was investigated by relating the results of repeated intravenous glucose tolerance tests to the phases of the oestrous cycle, namely anoestrus, pro-oestrus, oestrus and dioestrus. Neither the glucose tolerances nor the insulin responses were significantly different between these phases of the oestrous cycle in 12 Dalmatian bitches.     

Dexamethasone and prednisolone in the horse: pharmacokinetics and action on the adrenal gland

Pharmacokinetics of dexamethasone and prednisolone were studied in 6 horses given dexamethasone alcohol (IV or IM) or dexamethasone 21-isonicotinate as a solution IV or IM (50 micrograms/kg of body weight), prednisolone 21-sodium succinate IV or IM (0.6 mg/kg of body weight), or prednisolone acetate IM (0.6 mg/kg of body weight). Plasma concentrations were determined using a high-performance liquid chromatographic method. After dexamethasone alcohol (IV) or dexamethasone 21-isonicotinate (IV), the half-life of elimination was similar (53 minutes) for both formulations. After dexamethasone (alcohol and isonicotinate, IM), concentrations were low or nondetected. After prednisolone 21-sodium succinate (IV), the half-life of elimination (99.5 minutes) was significantly (P less than 0.01) longer than that for dexamethasone. After prednisolone 21-sodium succinate (IM), absorption was rapid and bioavailability was high. After prednisolone acetate (IM), absorption was slow and prednisolone was present in plasma for about 7 days. Due to the nonlinearity of prednisolone kinetics, a bioavailability higher than 100% was obtained. The basal plasma hydrocortisone concentration was approximately 70 ng/ml. After dexamethasone (IV or IM), plasma hydrocortisone values decreased after a 2-hour delay and returned to base line after a 3 to 4 day delay. After prednisolone 21-sodium succinate (IV or IM), plasma hydrocortisone decreased immediately (IV) or rapidly (IM) and returned to base line after a 24-hour delay. After prednisolone acetate (IM), plasma hydrocortisone decreased for up to 21 days.