High levels of inactive thymidine kinase 1 polypeptide detected in sera from dogs with solid tumours by immunoaffinity methods: implications for in vitro diagnostics.

Determination of serum thymidine kinase 1 (STK1) activity has been used as a proliferation marker for neoplastic diseases in both human and veterinary medicine. The purpose of this study was to determine STK1 activity and enzyme levels in different dog tumours. Serum samples from three dogs with leukaemia, five with lymphoma, 21 with solid tumours and 18 healthy dogs were analyzed for STK1 activity, using an optimized [(3)H]-deoxythymidine (dThd) phosphorylation assay, and for STK1 protein levels using an immunoaffinity/western blot assay. STK1 activity in dogs with haematological tumours was significantly higher than in the solid tumour and healthy dog groups (mean ± standard deviation [SD] = 65 ± 79, 1.1 ± 0.5, and 1.0 ± 0.4 pmol/min/mL, respectively). Serum samples were analyzed after immunoaffinity isolation by western blot and the TK1 26 kDa band intensities quantified revealing that concentrations were significantly higher in dogs with haematological tumours and solid tumours compared to healthy dogs (mean ± SD=33 ± 12, 30 ± 13, and 10 ± 5 ng/mL, respectively). Pre-incubation with the reducing agent dithioerythritol (DTE) showed a decrease in STK1 activity and protein levels in most samples, but an increase of about 20% in sera from healthy dogs and from those with haematological malignancies. Compared to animals with solid tumours, the specific STK1 activity (nmol [(3)H]-deoxythymidine monophosphate (dTMP)/min/mg of TK1 protein of 26 kDa) was 30-fold higher in haematological malignancies and 2.5-fold higher in healthy dogs, respectively. The results demonstrate that there is a large fraction of inactive TK1 protein, particularly in sera from dogs with solid tumours. The findings are important in the use of STK1 as a biomarker.

Clinical efficacy and safety of a water-soluble micellar paclitaxel (Paccal Vet) in canine mastocytomas.

OBJECTIVE: To determine the clinical efficacy and safety of a cremophor-free formulation of paclitaxel (Paccal Vet, Oasmia Pharmaceuticals) in dogs with mast cell tumours. METHODS: Paccal Vet was administered at a median dose of 145 (range, 135 to 150) mg/m(2) intravenously once every 21 days for three cycles to 29 dogs with macroscopic grade 2 or 3 mast cell tumour. Efficacy was assessed by tumour response (Response Evaluation Criteria in Solid Tumours version 1.0) and performance status score. Progression-free survival, quality of life and safety/adverse events were also evaluated. Clinical safety was assessed by clinicopathological analyses and recording of adverse events. RESULTS: Complete or partial response was observed in 59% of dogs. Performance status score remained constant or improved for 20 dogs and decreased by one grade for 9 dogs. Median time to progression was 247 (range, 42 to 268) days. Expected, transient frequently subclinical adverse events (primarily grade 3/4 neutropenia and grade 1/2 leukopenia) were observed in the majority of dogs. Nine dogs were euthanased and one dog died due to disease progression. CLINICAL SIGNIFICANCE: Paccal Vet appears to be a clinically safe and effective treatment for canine mast cell tumours. Further controlled confirmatory investigation is warranted.

A sensitive and kinetically defined radiochemical assay for canine and human serum thymidine kinase 1 (TK1) to monitor canine malignant lymphoma.

Thymidine kinase 1 (TK1) is a cell cycle regulated enzyme with maximum expression during the S phase. Serum TK1 (S-TK1) is a unique biomarker for cell proliferation. Here, an optimized [(3)H]-thymidine (dThd) phosphorylation assay is described, which is as sensitive as the commercially available TK-REA and TK-Liaison assays for measurement of S-TK1 activity in dogs and humans. Serum samples from dogs (35 healthy, 32 with lymphoma, 2 with leukemia, and 35 with solid tumors) and humans (18 healthy, 9 with chronic lymphocytic leukemia, 10 with myelodysplastic syndrome) were analyzed using the [(3)H]-dThd assay. Mean S-TK1 activities were 1.11 ± 0.46 pmol/min/mL in healthy dogs and 1.15 ± 0.32 pmol/min/mL in healthy humans. S-TK1 activities in dogs with hematological malignancies were 24.2 ± 47.9 pmol/min/mL, and the receiver operating characteristic curve showed an area under the curve of 0.88. With a cut-off value of 1.9 pmol/min/mL (mean value ± 2 SD), the sensitivity was 0.94 and the specificity was 0.68. Very similar results were obtained with human samples (healthy and lymphoma cases). S-TK1 activities measured during chemotherapy of six dogs with lymphoma were drastically reduced. In one case, S-TK1 activity increased prior to relapse. S-TK1 levels in dogs with solid tumors did not differ from the healthy group. S-TK1 activities correlated with those determined with the TK-REA and TK-Liaison assays (r=0.92 and r=0.96, respectively). In conclusion, this optimized [(3)H]-dThd assay is fast, sensitive and economical for measuring S-TK1 activity and should increase its clinical use as biomarker.

A randomized trial investigating the efficacy and safety of water soluble micellar paclitaxel (Paccal Vet) for treatment of nonresectable grade 2 or 3 mast cell tumors in dogs.

BACKGROUND: Effective treatments for dogs with advanced stage mast cell tumors (MCT) remain a pressing need. A micellar formulation of paclitaxel (paclitaxel [micellar]) has shown promise in early-phase studies. HYPOTHESIS/OBJECTIVES: The objective was to demonstrate greater activity for paclitaxel (micellar) compared with lomustine. The null hypothesis was µ(p) = µ(L) (ie, proportion of responders for the paclitaxel [micellar] and lomustine groups, respectively). ANIMALS: Two hundred and fifty-two dogs with advanced stage nonresectable grade 2 or 3 MCT. METHODS: Prospective multicenter randomized double-blind positive-controlled clinical trial. The primary endpoint was confirmed overall response rate (CORR) at 14 weeks. A secondary endpoint, biologic observed response rate (BORR), also was calculated. Safety was assessed by the characterization and grading of adverse events (AE). RESULTS: Overall CORR (7% versus 1%; P = .048) and BORR (23% versus 10%; P = .012) were greater for paclitaxel (micellar) compared with lomustine. Paclitaxel (micellar)-treated dogs were 6.5 times more likely to have a confirmed response and 3.1 times more likely to experience a biologic observed response. The majority of AE with paclitaxel (micellar) were transient and clinically manageable. Twenty-seven dogs (33%) receiving lomustine were discontinued because of hepatopathy compared with 3 dogs (2%) receiving paclitaxel (micellar) (P < .0001; odds ratio 26.7). CONCLUSIONS AND CLINICAL IMPORTANCE: Paclitaxel (micellar)'s activity and safety profile are superior to lomustine. The addition of an active and novel taxane to the veterinary armamentarium could fill a substantial need and, as its mechanism of action and AE profile do not overlap with currently available TKI, its availability could lead to effective combination protocols.

Effects on heart rate variability of isosorbide-5-mononitrate and metoprolol in patients with recent onset of angina pectoris.

BACKGROUND: Beta-blockers reduce sympathetic tone, increase vagal tone and improve prognosis in ischaemic heart disease. Nitroglycerin, being a vasodilator, may theoretically have an opposite effect and worsen the prognosis. The purpose of the present study was to analyse heart rate variability (HRV), which reflects autonomic tone, in angina patients on isosorbide-5-mononitrate (IS-5-MN) and/or metoprolol. METHODS AND RESULTS: Thirty-two patients (32-81 years old), with recently developed angina (median duration: 3 months), showing no other disease and on no drugs, were Holter-monitored 24-48 h at baseline and after 4-5 days on IS-5-MN (mean daily dose: 33 mg), on metoprolol (mean daily dose: 184 mg) and on the combined treatment. Recordings were analysed on the Marquette Series 8000 Holter scanner. Both IS-5-MN and metoprolol significantly reduced myocardial ischaemia (ST integral) and ventricular tachycardias. Metoprolol induced significant changes in the following parameters (baseline versus metoprolol): high-frequency peak 9 +/- 4 versus 11 +/- 4 ms (p < 0.001), low-to-high frequency ratio 2.5 +/- 0.6 versus 1.9 +/- 0.6 (p < 0.0001), root mean square of RR interval difference 23 +/- 7 versus 31 +/- 9 ms (p < 0.0001), RR intervals differing more than 50 ms from the preceding one 4.8 +/- 3.9 versus 10.0 +/- 7.0% (p < 0.0001), mean of all 5-min standard deviations 50 +/- 12 versus 56 +/- 11 ms (p < 0.001) and mean RR interval 819 +/- 90 versus 1,019 +/- 120 ms (p < 0.00001). The combined treatment caused approximately the same HRV changes as metoprolol alone. IS-5-MN had no significant effect on any HRV parameter, neither alone nor in combination with metoprolol. CONCLUSION: A clinically effective dose of metoprolol had potentially positive effects on HRV with increase in vagal and decrease in sympathetic tone while IS-5-MN had no effect on HRV, neither positive nor negative, neither alone nor in combination with metoprolol.

Short- and long-term prognosis after coronary artery bypass grafting in relation to smoking habits.

We describe the 2- and 5-year prognoses following coronary artery bypass grafting (CABG) in relation to smoking habits among consecutive patients being operated on in western Sweden during a 3-year period. Among the 2,121 patients, 10.2% admitted smoking at coronary angiography as compared with 7.5% 2 years after CABG (NS). Among smokers, the mortality during the subsequent 2 years was 8.9% as compared with 6.5% for exsmokers and 7.3% for never smokers (NS). During the 5-year follow-up, smokers had a mortality of 18.8% as compared with 13.6% for exsmokers and 12.5% for never smokers (p = 0.03). When correcting for dissimilarities in previous history, smoking was a strongly significant independent (p < 0.0001) predictor of 5-year mortality.

Death, mode of death, morbidity, and rehospitalization after coronary artery bypass grafting in relation to occurrence of and time since a previous myocardial infarction.

To describe the prognosis during 2 years after coronary artery bypass grafting (CABG) in relation to occurrence of and time since a previous acute myocardial infarction (AMI), data of all patients in western Sweden who underwent CABG without simultaneous valve surgery in the period June 1988-June 1991 were evaluated. In all, 2120 patients were included in the analyses. Of these, 1296 (61%) had a history of AMI and 127 (6%) had suffered an AMI within the last month before CABG. Mortality during the first 30 days after CABG was for patients with no previous AMI, previous AMI > 30 days prior to CABG, and previous AMI < or = 30 days prior to CABG 2.4%, 4.1%, and 5.5%, respectively (p < 0.05). The corresponding figures for the period between 30 days and 2 years after CABG were 3.6%, 4.4%, and 3.4% respectively (NS). In a multivariate analysis among patients with a previous AMI, a recent infarction (< or = 30 days prior to CABG) did not turn out as an independent predictor of death during 2 years of follow-up. A history of AMI was associated with increased mortality during the first 30 days but not thereafter, but recent AMI was not an independent predictor of total 2-year mortality.

Mortality and morbidity in diabetic and nondiabetic patients during a 2-year period after coronary artery bypass grafting.

OBJECTIVE: To describe mortality and morbidity during a 2-year period after coronary artery bypass grafting (CABG) among diabetic and nondiabetic patients. RESEARCH DESIGN AND METHODS: All the patients in western Sweden in whom CABG was undertaken between June 1988 and June 1991 and in whom concomitant procedures were not performed were registered prospectively. The study was a prospective follow-up. RESULTS: Diabetic patients (n = 268) differed from nondiabetic patients (n = 1,859) in that more women were included, and the patients more frequently had a previous history of myocardial infarction (MI), hypertension, congestive heart failure, intermittent claudication, and obesity. Diabetic patients more frequently required reoperation and had a higher incidence of peri- and postoperative neurological complications. Mortality during the 30 days after CABG was 6.7% in diabetic patients versus 3.0% in nondiabetic patients (P < 0.01). Mortality between day 30 and 2 years was 7.8 and 3.6%, respectively (P < 0.01). During 2 years of follow-up, a history of diabetes appeared to be a significant independent predictor of death. Whereas the development of MI after discharge from the hospital did not significantly differ between the two groups; 6.3% of diabetic patients developed stroke versus 2.5% in nondiabetic patients (P < 0.001). CONCLUSIONS: Diabetic patients have a mortality rate during the 2-year period after CABG that is about twice that of nondiabetic patients during both the early and late phase after the operation.

Improvement in quality of life and exercise capacity after coronary bypass surgery.

BACKGROUND: Outcome after coronary artery bypass grafting is usually evaluated by exercise stress testing. Increased exercise capacity and reduced angina pectoris have been equated with improved quality of life, but this represents a limited view. OBJECTIVE: To prospectively evaluate the effects of coronary artery bypass grafting on quality of life and exercise capacity and their interrelationship. METHODS: In a consecutive series of patients (N = 2365) who underwent coronary artery bypass grafting, we administered a questionnaire to assess quality of life before and 2 years after surgery. A standardized exercise test was performed during the year before surgery and 2 years after. A preoperative exercise test was performed by 726 patients. Among these patients, 462 completed a quality-of-life questionnaire preoperatively and 578 did so postoperatively. Preoperative and postoperative exercise tests were obtained from 362 patients. RESULTS: The improvement in quality of life was related to the severity of preoperative angina (P < .001) and female sex (P = .004) and was inversely related to preoperative exercise performance (P = .04). The improvement in exercise capacity was greater among men (P < .001) and was inversely related to preoperative exercise capacity (P < .001). CONCLUSIONS: The greatest improvement in quality of life after coronary artery bypass grafting appeared in those patients with the most impaired exercise capacity, those with the most severe angina pectoris, and women. Improvement in exercise capacity was greatest in patients with the poorest preoperative exercise capacity and in men. These findings indicate that exercise testing is of limited value as a measure of quality of life and that assessment by a questionnaire has a complementary place.