Milk antimicrobial residues are a serious concern for the dairy industry. Residues of the tetracycline family of antimicrobials have been reported in market milk by investigators, using radioimmunoassay and microbial receptor technology (hereafter referred to as the Charm II test). In response to these reports, an investigation was conducted to determine the potential of 3 extra-label routes of oxytetracycline (OTC) administration to cause milk residues above the Food and Drug Administration safe value of 30 parts per billion (ppb). Lactating Holstein cows were administered OTC once by use of 1 of 3 routes: IV at 16.5 mg/kg of body weight (n = 6); IM at 11 mg/kg (n = 6); and intrauterine (IU) at 2 g in 500 ml of saline solution/cow (n = 6). Duplicate milk samples were collected at the milking prior to drug administration and for the next 13 milkings at 12-hour intervals. Concentrations of OTC in milk samples were analyzed by use of the Charm II test for tetracyclines (limit of OTC detection, approx 5 ppb) and were compared with concentrations determined by use of a high-performance liquid chromatography (HPLC) method (lower limit of OTC quantitation, approx 2 ppb). The potential for milk OTC residues above the Food and Drug Administration safe value of 30 ppb after treatment was considerably greater for the IV and IM routes, compared with the IU route. Mean peak OTC concentrations in milk at the first milking after treatment for the HPLC and Charm II tests were approximately 3,700 to 4,200 ppb for the IV route, 2,200 to 2,600 ppb for the IM route, and 186 to 192 ppb for the IU route, respectively. Pharmacokinetic analysis, based on milk OTC concentrations, indicated that the area under the curve (AUC) and milk maximal concentration (Cmax) differed significantly (P < 0.001) among routes of administration. The AUC was similar for IV and IM administrations; values for both were greater than the AUC for IU administration. The Cmax was greatest for IV, intermediate for IM, and least for IU administration. There were significant (P less than or equal to 0.01) differences in AUC between assay methods (Charm II vs HPLC) for the IV route. Concentrations of OTC in milk determined by the Charm II test were often greater than those determined by HPLC. Administration of OTC to lactating cows via these routes is extra-label drug use. Failure to withhold the product from early milkings of cows administered OTC by the IV or IM route should be considered a potential cause of OTC residues in market milk. Milk from nearly all cows contained OTC (< 30 ppb), the Food and Drug Administration safe level, by 120 hours after OTC administration. Use of appropriate withholding times and antibiotic residue testing is indicated to avoid OTC residues.

Two techniques for evaluating argyrophilic nucleolar organizer regions (AgNOR) were compared on 74 canine mammary tumors to discriminate between benign and malignant lesions. For each lesion, direct counting of AgNOR on at least 100 cell nuclei was compared with area, perimeter, and integrated optical density AgNOR dot values determined by image analysis. Significant differences between benign and malignant tumors were observed with both methods; however, lesions determined as aggressive or proliferative by histologic evaluation were only singled out by image analysis measurements. Image analysis, in our hands, was a reliable, precise, and convenient technique to characterize malignancy in canine mammary tumors.

Using 7 penicillins (amoxicillin, ampicillin, methicillin, penicillin G, oxacillin, cloxacillin, and dicloxacillin), simultaneous and direct determination of residual penicillins in biological samples was carried out by use of bioassay and high-performance liquid chromatography with spectrophotometric or fluorometric detectors. By use of assay medium seeded with penicillin-sensitive Micrococcus luteus (ATCC No. 9341) as a test organism, we were able to detect penicillins even at low concentrations. All penicillins treated with 10 U of penicillinase/ml did not produce inhibition zones by disk testing, even at a concentration of 100 micrograms of penicillin/ml/assay plate. Using a mobile phase of acetonitrile:methanol:0.01M KH2PO4 (19:11:70, v/v/v; pH, 7.1), standard solutions of the penicillins were separated from each other by use of high-performance liquid chromatography analysis, producing symmetric peaks without tailing, each of which had a characteristic retention time. Simultaneous detection of residual penicillins in bovine serum, kidneys, and liver, for the 5 penicillins for which analysis was possible by use of the UV method, yielded recovery rates from 71.4 to 102.3%; for the 2 amino-penicillins, amoxicillin and ampicillin, which could only be detected by use of the fluorometric method, recovery rate ranged from 72.9 to 103%.

The ICP4 homolog of Marek's disease virus (MDV ICP4) is a possible candidate for the transactivator of the early genes. We transfected MDCC-MSB-1 (MSB-1) tumor cells with plasmid including a coding region of MDV ICP4 using cationic liposome. As carriers for intranulear transport, high mobility group -1 and -2 proteins were bound to the plasmid DNA before forming liposomes. We detected transcripts from the plasmid 2 hr after transfection by quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) analysis. We also detected abundant transcripts of endogenous ICP4 2-96 hr after transfection. These data suggested that expression of introduced MDV ICP4 gene enhanced the expression of endogenous MDV ICP4. On the other hand, quantitative PCR analysis for virus genome DNA indicated no significant alteration of copy number of virus genome in transfected MSB-1 cells, suggesting that reactivation of virus requires more than turning on MDV ICP4 gene

This study ws carried out to determine the effects of supplementation of the maturation media with insulin on in vitro maturation and fertilization of bovine oocytes. In Experiment 1, cumulus-intact bovine oocytes were cultured in a maturation medium (TCM-199 containing 10% fetal calf serum, 0.02 U/ml follicular stimulating hormone and 1 mu-g/ml estradiol-17beta) with or without insulin supplementation (10 mu-g/ml). The maturation and fertilization rates of oocytes and subsequent embryonic development to the blastocyst stage were not affected by the treatment with insulin in the presence of serum and the hormones during the maturation period. In Experiment 2, to avoid the effects of serum and the hormones, a serum- and hormone-free maturation medium (TCM-199 containing 1 mg/ml polyvinyl alcohol) was used. In the absence of serum and hormones during the maturation period, the maturation rate was not affected by treatment with insulin, but the fertilization rate was improved. In Experiment 3, when denuded oocytes were inseminated together with cumulus cells cultured in serum- and hormone-free maturation medium supplemented with insulin, the fertilization rate was increased. These results demonstrate that the addition of insulin to the serum- and hormone-free maturation medium improves the fertilization rate of bovine oocytes in vitro, and suggest that insulin may stimulate the secretion of sperm capacitating agent(s) from cumulus cells

Between January and april, 1992, two captive Bennett's wallabies (Macropus rufogriseus) from a wildlife park in Iwamizawa City, Hokkaido, Japan, were diagnosed as having nutritional myopathy. One wallaby, four-year-old adult male, had mild fresh lesions, confined to the skeletal muscles, with poor cell reaction. The other wallaby, 8-month-old female joey, had marked and extensive lesions with cellular reactions and regenerative muscle fibers in the locomotor muscles. Involvement of other striated muscles such as those of the tongue, diaphragm and heart was mild with minimal cellular reaction. Age susceptibility may account for the difference in the extent of severity of the lesions between these two animals

An efficacy trial of Cymelarsan (R) on a Zambian strain of Trypanosoma brucei brucei was done. Twenty-five male mice were infected intraperitoneally with 10(6) of T. b. brucei isolated from a dog. Five groups of 5 mice were treated with 0 (control), 0.25, 0.5, 1.0 and 2.0 mg/kg cymelarsan, respectively. The target was to achieve aparasitaemia for 30 days post-treatment, euthanising those that remained parasitaemic or relapsed before then. The 0.25 and 0.5 mg/kg groups remained parasitaemic although the parasitaemic levels were reduced. The 1.0 mg/kg group had a proportion of aparasitaemic mice. However, all mice in the 2.0 mg/kg group remained aparasitaemic until day 20 when 2 mice relapsed. These results suggested that more than 2.0 mg/kg was required to eliminate this strain

The influence of increasing the physical electrofusion parameters, direct current (DC) pulse strength, pulse duration, pulse number, alternating current (AC) voltage and alignment time, in electrolytes on the rates of fusion,degeneration and development of zona-free mouse 2-cell embryos were examined. Furthermore, the effects of physiological saline and mannitol as fusion media and various mouse strains were also evaluated. Dulbecco's phosphate-buffered saline (PBS) supplemented with 10% fetal calf serum was used as the main fusion solution. A significant increase in the rate of fusion (P0.05) was obtained by increasing pulse strength from 30 to 300 V/mm. The embryos fused at the pules strengths of 30 to 70 V/mm had significantly higher development rates to blastocysts compared with those fused at 100 to 300 V/mm (P0.05). There were no significant differences in the rates of fusion, degeneration and d development to blastocysts when the pulse duration was increased from 30 to 90 mu-sec. Although fusion rates were increased (P0.05) by increasing the pulse number up to 4, a significant decrease (P0.05) in development to blastocysts was observed when the pulse number was 5. Application of AC voltage prior to the DC pulse tended to increase the fusion rate (89.2-93.8%), compared with fusion with the DC pulse only (75.0%). Prolongation of alignment time from 5 to 15 sec had no effect on the fusion rate. Under the optimum conditions (2 pulses of DC of 7- V/mm, 70 mu-sec pulse duration and AC of 5 V/mm for 5 sec), no significant difference was obtained in the fusion and development rates in different mouse strains, nor were fusion and development rates significantly different among PBS, physiological saline and mannitol solutions (P0.05)