Monitoring unfractionated heparin therapy in dogs by measuring thrombin generation

BACKGROUND

The calibrated automated thrombogram (CAT), an assay that permits measurement of thrombin generation in plasma, may be useful in studying hemostatic disorders and anticoagulant therapy in animals.

OBJECTIVES

The aims of the study were to measure thrombin generation in healthy Beagle dogs and to evaluate the potential use of the CAT assay for monitoring therapy with unfractionated heparin (UFH).

METHODS

Individual platelet-poor plasma samples and a plasma pool from 20 healthy adult Beagles were prepared. Serial UFH plasma dilutions were used to establish an in vitro heparin-sensitivity curve. The pharmacodynamic effects of heparin in vivo were evaluated in Beagles using the CAT assay to measure thrombin generation with tissue factor at a concentration of 5 pM for initiation.

RESULTS

In healthy Beagles, the range of endogenous thrombin potential (ETP) was 238.7-414.0 nM/min (mean ± SD, 340.4 ± 63.1 nM/min). ETP intra-assay and interassay variations were 7.1% and 12.9%, respectively. In vitro, a UFH concentration ≥0.4 U/mL resulted in total inhibition of thrombin generation. In vivo, the maximal effect of UFH on ETP was observed at 170 ± 36 minutes (range, 120-210 minutes) and resulted in a decrease in ETP of 38.5 ± 7.8% (range, 26.5-50.3%). In 210-420 minutes, ETP returned to baseline in 5 dogs.

CONCLUSION

Our study demonstrates that thrombin generation can be measured in canine plasma and may be useful in assessing the degree of anticoagulation provided by UFH.

Clinical application of Patlak plot CT-GFR in animals with upper urinary tract disease

Glomerular filtration rate (GFR), an important parameter of renal function, is difficult to assess clinically. Serum creatinine and blood urea nitrogen measurements lack sensitivity, whereas radionuclide determination of GFR is not always available and requires postinjection patient isolation. GFR can be determined using computed tomography (CT), most commonly via Patlak plot analysis. Four adult cats, two adult dogs, and a foal underwent abdominal CT under general anesthesia for various diseases of the upper urinary tract. CT-GFR was measured with a single-slice dynamic acquisition and Patlak plot analysis. In five animals, the total CT-GFR appeared to be below normal, corresponding with mild (two animals) and moderate (two animals) increases of serum creatinine in four. In the two animals with normal or increased CT-GFR, serum creatinine was within the reference values. A significant negative logarithmic relationship was found between CT-GFR and serum creatinine values (P = 0.008; r2 = 0.75). No complications occurred during or following CT-GFR. CT examination provided clinically relevant information in 3/5 patients with possible ureteral obstruction and in 3/3 patients with suspected ureteral calculi. Single-slice dynamic CT-GFR was practical and provided clinically useful information in this small series of patients undergoing CT of the upper urinary tract. There was a significant relationship between CT-GFR and serum creatinine values, which supports the clinical potential of CT-GFR and justifies further investigation of this technique.

The potential of subterranean microbes in facilitating actinide migration at the Grimsel Test Site and Waste Isolation Pilot Plant

Microorganisms may affect the long-term stability and mobility of radionuclides disposed of in deep geological formations. Of particular concern is the association of radionuclides with subterranean microbial cells and their subsequent transport as biocolloids. We characterized the total microbial populations in two groundwater samples: one from the Culebra dolomite member of the Rustler Formation at the Waste Isolation Pilot Plant (WIPP), NM, and the other from the granitic formation at the Grimsel Test Site (GTS), Switzerland. Culebra groundwater (ionic strength 2.8 M, pH 7) contained 1.51 ± 1.08 × 105cells ml-1, with a mean cell length of 0.75 ± 0.04 μm and width of 0.58 ± 0.02 μm. In contrast, low ionic-strength GTS groundwater (0.001 M, pH 10) contained 3.97 ± 0.37 × 103cells ml-1, with a mean cell length of 1.50 ± 0.14 μm and width of 0.37 ± 0.01 μm. Adding appropriate electron donors and acceptors to the groundwaters facilitated the growth of aerobic, denitrifying, fermentative, and acetogenic microorganisms. Uranium biosorption was studied in two isolates from these groundwaters, as well as several pure cultures from saline and non-saline environments. Halophilic and non-halophilic bacteria exhibited differences in the amount of U associated with the cells. Plutonium uptake by Acetobacterium sp. isolated from GTS varied from 30 - 145 pg of Pu mg-1dry weight of cells.

Effects of prednisone on blood lactate concentrations in healthy dogs

BACKGROUND

Glucocorticoids affect carbohydrate and lactate metabolism.

HYPOTHESIS

Administration of prednisone to healthy dogs will result in clinically relevant hyperlactatemia.

ANIMALS

Twelve healthy adult Beagle dogs.

METHODS

Prospective, controlled experimental study. Twelve healthy adult Beagles were divided into 2 groups (3 of each sex per group). One group served as control. The other group received 2 treatments: low, 1 mg/kg prednisone PO q24h for 2 weeks; high, 4 mg/kg prednisone PO q24h for 2 weeks. A washout period of 6 weeks separated the treatments. Blood samples were drawn for whole blood lactate measurement on day (D) 0, D4, and D14 and measured in duplicate.

RESULTS

Compared with the control group, low and high groups had significantly higher blood lactate concentrations at D4 and D14. There was no difference at D0. There was no effect of time within the control group. In the low and high groups, blood lactate concentration was increased at D4 and D14 versus D0. Blood lactate concentration was greater in the high group than the low group at D14 only.

CONCLUSIONS AND CLINICAL IMPORTANCE

Dogs treated with prednisone experience statistically significant increases in blood lactate concentrations, which can result in type B hyperlactatemia. In such cases, improving tissue perfusion, treatment for the commonest form of hyperlactatemia (type A) would be unnecessary.

Plateletworks: a screening assay for clopidogrel therapy monitoring in healthy cats

Plateletworks is a screening assay used in human medicine to monitor platelet-inhibiting drugs. As arterial thromboembolism is a common complication in cats suffering from cardiomyopathy, they are often treated with anti-platelet medication. Clopidogrel (Plavix), an anti-platelet aggregation drug, has recently been evaluated in healthy cats. The purpose of this study was to determine if the Plateletworks method can detect a decrease in platelet aggregation in cats receiving clopidogrel. Nine healthy adult cats were used for this study. Platelet aggregation was measured before and after a 3-day clopidogrel treatment (18.75 mg SID). Platelet aggregation after the clopidogrel treatment was significantly lower (P < 0.01). The Plateletworks method appears to be a promising test to monitor clopidogrel therapy in cats.

N-acetyl-beta-D-glucosaminidase index as an early biomarker for chronic kidney disease in cats with hyperthyroidism

BACKGROUND

Hyperthyroid cats are at risk of developing azotemic chronic kidney disease (CKD) and diagnostic tools currently used to screen for CKD in hyperthyroid cats are either unreliable or impractical.

HYPOTHESIS

Urine N-acetyl-beta-D-glucosaminidase index (NAG(i)) is a good biomarker for azotemic CKD in hyperthyroid cats.

ANIMALS

Twenty-four newly diagnosed nonazotemic hyperthyroid cats and 10 healthy cats.

METHODS

All cats were evaluated for hyperthyroidism at baseline. Hyperthyroid cats were treated with methimazole and reevaluated once euthyroid. At the end of the study, cats were divided into 3 groups: healthy cats, nonazotemic, and azotemic euthyroid cats. Baseline group characteristics were compared to predict azotemic CKD. The influence of treatment on NAG(i) was evaluated.

RESULTS

Baseline NAG(i) was significantly different among groups (P= .004). Azotemic cats had a higher median value (13.12 U/g) when compared with healthy cats (1.38 U/g). With NAG(i) >2.76 U/g, negative and positive predictive values for development of azotemia were 77.7 and 50%, whereas the combination of a urine specific gravity (USG) <or=1.035 and T(4) >7.80 microg/dL enhanced predictive values to 88.9 and 83.3%, respectively. NAG(i) values decreased significantly over time in treated nonazotemic cats.

CONCLUSIONS AND CLINICAL RELEVANCE

Baseline NAG(i) did not differentiate azotemic from nonazotemic euthyroid cats. NAG(i) could be used to assess renal function during medical therapy allowing the clinician to adjust methimazole dosage accordingly. The combination of USG and T(4) could optimize identification of appropriate candidates for permanent treatment of hyperthyroidism.

A retrospective study of canine persistent nasal disease: 80 cases (1998-2003)

Persistent canine nasal disease is a common complaint in small animal practice; however, an etiologic diagnosis can be difficult to establish. The aim of this retrospective study was to determine the percentage of cases for which the etiology was determined in our hospital population. Medical records from 80 dogs met the criteria of inclusion in the study. Nonspecific rhinitis was identified in 23.7% of cases. Other diagnoses were neoplasia (15.0%), fungal infection (nasal aspergillosis) (8.7%), cleft palate (8.7%), periodontal disease (4.0%), parasites (1.3%), foreign body (1.3%), and primary bacterial disease (1.3%). A definitive diagnosis could not be established in 36.3% of cases. Dogs with neoplastic and mycotic diseases often presented with severe radiographic and rhinoscopic lesions. Despite a systematic approach, numerous cases went undiagnosed. The use of advanced imaging should increase our ability to obtain an etiologic diagnosis in canine nasal disease.

Group G streptococcal toxic shock-like syndrome in three cats

Three 8-week-old kittens were presented with a history of acute, generalized weakness and severe fever. One cat was dead upon presentation, and necropsy findings were supportive of a group G Streptococcus spp. septicemia. During their clinical courses, two of the three kittens developed a progressive, marked swelling of one or more limbs. One moribund and severely hypothermic cat was euthanized a few hours after presentation, and necropsy was also supportive of a group G Streptococcus spp. septicemia. One kitten recovered. Group G streptococcal toxic shock-like syndrome was suspected because of the fulminant progression of the septicemia.

Phase II trial of patients (pts) with extensive stage small cell lung cancer (ES-SCLC) immunized with p53-transduced dendritic cells (p53-DC): Immune sensitization to chemotherapy (CT)

3012

Background: Although ES-SCLC is initially, very responsive to CT, responses are not durable and relapse is characterized by chemoresistance. High incidence of p53 gene mutations, which prolong the protein’s half life, result in its frequent overexpression and enhanced detection in SCLC cells. This in turn allows for their recognition by p53-specific cytotoxic T cells. Here, we evaluated the clinical and immune response of a vaccine (vac) using p53-DC. Methods: Eligibility: Untreated, ES-SCLC pts. Age = 18 years. Performance status (PS) 0–2. Treated and controlled brain metastases. Adequate renal, hepatic and bone marrow function. Toxicity (T), survival (MST) and clinical and p53- specific immune responses were determined by CTCAE v2.0, Kaplan-Meier, RECIST and ELISPOT and tetramer staining respectively. Pts first received CT to best clinical response. Eight weeks later, those with minor progression (PD) or better, underwent leukapheresis. DC, generated from peripheral blood precursors, were infected with an adenoviral construct containing p53 (Advexin; Ad-p53) to produce the p53-DC vac. Each vaccination consisted of subcutaneous injections in 4 different nodal basins every 2 weeks x3 (2–5×106 p53-DC/dose). Results: Thirty-six pts received at least one vac; median age=58.8, (range=39–79), M/F=13/23, PS 0/1=16/20. All pts were evaluable for T and MST. Total vac=127 (median=3, range=2–6). Overall, vac was well tolerated (no > grade 2 toxicities detected). p53-specific immune response was positive in 11/21 (52.4%) pts; pending in 15 pts. After 3 vac doses, 10 (27.7%) pts. had stable disease (SD) and 26 (72.2%) had PD. Pts with SD were re-vaccinated (x3). Upon PD, all pts were offered further CT. Clinical response to post-vac CT was evaluated in 22 pts. Ten pts (45%) responded to post-vac CT (second line=7, third line=3) and 6 pts had SD. MST=473 days (95% CI: 380,534). Conclusions: ES-SCLC pts were treated safely with p53-DC vaccine and demonstrated significant immune response. The p53-DC vaccine appears to sensitize ES-SCLC to subsequent CT resulting in improved survival.

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Evaluation of coagulation markers in the plasma of healthy cats and cats with asymptomatic hypertrophic cardiomyopathy

BACKGROUND

Thrombosis and arterial thromboembolism are frequent complications of feline cardiomyopathy, especially when associated with left atrial enlargement. Markers of activated coagulation may be used to evaluate the coagulation status of cats with hypertrophic cardiomyopathy (HCM) in relation to left atrial size.

OBJECTIVES

The objective of this study was to compare plasma concentrations of thrombin-antithrombin complex (TAT), D-dimer, and fibrin degradation products (FDP) between clinically healthy cats and cats with HCM. Prothrombin time (PT), activated partial thromboplastin time (aPTT), and antithrombin activity were also compared and the association between left atrial (LA) size and coagulation results in cats with HCM was evaluated.

METHODS

Blood samples from 19 clinically healthy cats and 20 cats with HCM were obtained. All cats with HCM were asymptomatic and had no signs of heart failure. LA diameter and LA to proximal aortic (Ao) diameter ratio (LA:Ao) were determined by echocardiography.

RESULTS

Reference intervals for D-dimer and TAT concentrations in plasma of healthy cats were established as 0.09-0.32 microg/mL and 2.0-20.0 microg/L, respectively. TAT, D-dimer, and FDP concentrations were increased in 5, 3, and 2 cats with HCM, respectively. TAT and D-dimer concentrations, and PT and aPTT were not significantly different between groups. Antithrombin activity was significantly decreased in cats with HCM (P=.03) despite marked range overlap. LA and LA:Ao were not correlated with coagulation results.

CONCLUSIONS

Laboratory evidence of hypercoagulability was found in 45% of cats with HCM. Left atrial size was not associated with laboratory evidence of hypercoagulability. Association between coagulation markers and risk of thrombosis has yet to be evaluated in cats with HCM.

Pericardial effusion associated with an appropriately placed umbilical venous catheter

Central venous catheterization is widely used in neonatal intensive care units to support tiny preterm babies. Pericardial effusion (PCE) and cardiac tamponade are uncommon but potentially fatal complications of percutaneous, umbilical and surgically placed central venous catheters related to intracardiac position or migration. This report describes a case of PCE arising from fluid infused via umbilical venous catheter. The case study highlights two important aspects: one, occurrence of PCE in a baby with satisfactory position of the umbilical catheter, and second, the life-saving application of basic echocardiography by bedside caregivers for the diagnosis and treatment of this critical condition.

National survey of doses from CT in the UK: 2003

A review of patient doses from CT examinations in the UK for 2003 has been conducted on the basis of data received from over a quarter of all UK scanners, of which 37% had multislice capability. Questionnaires were employed to collect scan details both for the standard protocols established at each scanner for 12 common types of CT examination on adults and children, and for samples of individual patients. This information was combined with published scanner-specific CT dose index (CTDI) coefficients to estimate values of the standard dose indices CTDI(w) and CTDI(vol) for each scan sequence. Knowledge of each scan length allowed assessment of the dose-length product (DLP) for each examination, from which effective doses were then estimated. When compared with a previous UK survey for 1991, wide variations were still apparent between CT centres in the doses for standard protocols. The mean UK doses for adult patients were in general lower by up to 50% than those for 1991, although doses were slightly higher for multislice (4+) (MSCT) relative to single slice (SSCT) scanners. Values of CTDI(vol) for MSCT were broadly similar to European survey data for 2001. The third quartile values of these dose distributions have been used to derive UK national reference doses for examinations on adults (separately for SSCT and MSCT) and children as initial tools for promoting patient protection. The survey has established the PREDICT (Patient Radiation Exposure and Dose in CT) database as a sustainable national resource for monitoring dose trends in CT through the ongoing collation of further survey data.