Pharmacologic evaluation of ammonium tetrathiomolybdate after intravenous and oral administration to healthy dogs.

OBJECTIVE: To evaluate pharmacokinetics of ammonium tetrathiomolybdate (TTM) after IV and oral administration to dogs and effects of TTM administration on trace mineral concentrations. ANIMALS: 8 adult Beagles and Beagle crossbreds (4 sexually intact males and 4 sexually intact females). PROCEDURES: Dogs received TTM (1 mg/kg) IV and orally in a randomized crossover study. Serum molybdenum and copper concentrations were measured via inductively coupled plasma mass spectrometry in samples obtained 0 to 72 hours after administration. Pharmacokinetics was determined via noncompartmental analysis. RESULTS: For IV administration, mean ± SD terminal elimination rate constant, maximum concentration, area under the curve, and half-life were 0.03 ± 0.01 hours(-1), 4.9 ± 0.6 µg/mL, 30.7 ± 5.4 µg/mL•h, and 27.7 ± 6.8 hours, respectively. For oral administration, mean ± SD terminal elimination rate constant, time to maximum concentration, maximum concentration, area under the curve, and half-life were 0.03 ± 0.01 hours(-1), 3.0 ± 3.5 hours, 0.2 ± 0.4 µg/mL, 6.5 ± 8.0 µg/mL•h, and 26.8 ± 8.0 hours, respectively. Oral bioavailability was 21 ± 22%. Serum copper concentrations increased significantly after IV and oral administration. Emesis occurred after IV (2 dogs) and oral administration (3 dogs). CONCLUSIONS AND CLINICAL RELEVANCE: Pharmacokinetics for TTM after a single IV and oral administration was determined for clinically normal dogs. Absorption of TTM after oral administration was variable. Increased serum copper concentrations suggested that TTM mobilized tissue copper. Further studies will be needed to evaluate the potential therapeutic use of TTM in copper-associated chronic hepatitis of dogs.

Association between Mycoplasma-specific polymerase chain reaction assay results and oral bacterial contamination of bronchoalveolar lavage fluid samples from dogs with respiratory tract disease: 121 cases (2005-2012).

OBJECTIVE: To determine whether an association exists between oral bacterial contamination of bronchoalveolar lavage fluid (BALF) and positive PCR assay results for the detection of Mycoplasma spp in BALF samples of dogs with lower respiratory tract (LRT; portion from the trachea to the lungs) disease. DESIGN: Retrospective case series. ANIMALS: 121 dogs with LRT disease. Procedures-Medical records from January 2005 to April 2012 were reviewed. Dogs with LRT disease that had BALF samples evaluated by use of Mycoplasma-specific PCR assay, bacterial culture, and cytologic examination were included. Information on signalment, final diagnoses, and BALF testing results was extracted. RESULTS: 83 (68.6%) dogs had BALF samples with negative PCR assay results for Mycoplasma spp, and 38 (31.4%) had positive results. The BALF samples with cytologic evidence of oral bacterial contamination were 5.1 times as likely to have positive Mycoplasma-specific PCR assay results as were noncontaminated samples. Compared with hound or herding dogs, other breeds were 13.6 times as likely to have positive PCR assay results. Dogs with bronchitis were less likely than dogs with other LRT diseases to have positive Mycoplasma-specific PCR assay results. No significant association was found between Mycoplasma-specific PCR assay results and bacterial culture results. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs with LRT disease, Mycoplasma-specific PCR assay results for BALF samples should be interpreted in terms of possible oral bacterial contamination. Mycoplasma-specific PCR assay of BALF samples from herding dogs, hound dogs, and dogs with bronchitis may be less rewarding than for other dogs with LRT disease.

Molecular changes associated with the acquisition of oestrogen hypersensitivity in MCF-7 breast cancer cells on long-term oestrogen deprivation.

The growth dependence of many breast cancers on oestrogen has been exploited therapeutically by oestrogen deprivation, but almost all patients eventually develop resistance largely by unknown mechanisms. Wild-type (WT) MCF-7 cells were cultured in oestrogen-deficient medium for 90 weeks in order to establish a long-term oestrogen-deprived MCF-7 (LTED) which eventually became independent of exogenous oestrogen for growth. After 15 weeks of quiescence (LTED-Q), basal growth rate increased in parallel with increasing oestrogen sensitivity. While 10(-9)M oestradiol (E2) maximally stimulated WT growth, the hypersensitive LTED (LTED-H) were maximally growth stimulated by 10(-13)M E2. By week 50, hypersensitivity was apparently lost and the cells became oestrogen independent (LTED-I), although the pure antioestrogen ICI182780 still inhibited cell growth and reversed the inhibitory effect of 10(-9)M E2 at 10(-12) to 10(-7)M. Tamoxifen (10(-7) to 10(-6)M) had a partial agonist effect on WT, but had no stimulatory effect on LTED. Whilst LTED cells have a low progesterone receptor (PgR) expression in all phases, oestrogen receptor (ER) a expression was, on average, elevated five- and seven-fold in LTED-H and LTED-I, respectively, and serine118 was phosphorylated. ERbeta expression was up-regulated and the levels of insulin receptor substrate 1 (IRS-1) remained low throughout all phases. The levels of RIP140mRNA appeared to decrease to approximately 50% of the WT message in LTED-Q and remained constant into the hypersensitive phase. No significant changes were observed in the expression of SUG-1, TIF-1 and SMRT in LTED. The overall changes in nuclear receptor interacting proteins do not appear to be involved in the hypersensitivity. Thus, the resistance of these human breast cancer cells to oestrogen-deprivation appears to be due to acquired hypersensitivity which may be explained in part by increased levels of and phosphorylated ERalpha.