Fractional excretion tests: a critical review of methods and applications in domestic animals

The fractional excretion (FE) of a constituent by the kidney is the fraction of the amount filtered by the glomerulus, which is excreted into urine. It is mostly determined for electrolytes, and is expressed as the ratio of the clearance of a given electrolyte to creatinine clearance. The main physiologic factors affecting FE variation are species, age, and the alimentary supply of electrolytes. The value of FE tests in the diagnosis of kidney disease is limited, except in canine Fanconi's syndrome. FEs of many constituents often are increased in chronic kidney disease, but their diagnostic value is no greater than that of plasma creatinine concentration. FEs also are altered in nonrenal diseases such as diabetes mellitus and rhabdomyolysis, and during treatment with xylazine, rehydration fluids, and diuretics. FEs, especially of calcium, phosphates, and magnesium, are useful in clinical nutrition to assess mineral balance. FE is difficult to measure, so its use should be limited to nutritional investigations and nephrology research.

Teaching veterinary clinical pathology to undergraduate students: an integrated European project

BACKGROUND

Veterinary clinical pathology is a relatively new and emerging discipline in Europe that has gained momentum with the recent establishment of a specialty college. In this situation, veterinary faculties may face challenges in understanding and defining what clinical pathology is and how it can best be integrated into existing curricula. In addition, many schools in Europe may not yet have available a critical mass of suitably qualified faculty capable of teaching in all areas of clinical pathology.

OBJECTIVE

The main purpose of this report is to describe the goals, procedures adopted, teaching material produced, and proposed future activities of a major European initiative designed to develop a veterinary clinical pathology curriculum.

METHODS

Four working subgroups were formed to establish a list of course objectives and topics and prepare a series of lectures. These contents were reviewed and discussed several times at a series of general meetings.

RESULTS

An undergraduate course on veterinary clinical pathology was designed with course objectives, a list of topics and a CD-ROM consisting of 24 lectures.

CONCLUSIONS

The results of this project could be useful in the establishment or improvement of training programs in veterinary clinical pathology at the undergraduate level in Europe and in other places around the world. The provision of teaching resources for faculty could help to instill in veterinary students a strong understanding of the discipline and promote development of advanced training programs and career opportunities in clinical pathology in Europe.

Comparison of measurements of canine plasma glucose, creatinine, urea, total proteins, alanine aminotransferase, and alkaline phosphatase obtained with the APOLOWAKO and Vitros 250 analyzers

The APOLOWAKO is an entirely automatic benchtop biochemistry analyzer that uses stabilized liquid reagents. It was tested for canine blood and plasma glucose, creatinine, urea, total proteins, alanine aminotransferase, and alkaline phosphatase. The APOLOWAKO gave very similar results for whole blood and the corresponding plasma (n=32). Within-laboratory imprecision was below 2.2% and 5.8% for substrates and enzymes, respectively. Comparison of results with whole blood by APOLOWAKO and with the corresponding plasma by Vitros 250 (n=139) showed very good correlations. Passing-Bablok's regression slopes ranged from 0.83 to 1.12 and intercepts were close to zero, except for ALP where the results obtained by APOLOWAKO were approximately 1.5 times higher than by Vitros. The APOLOWAKO system can be a reliable instrument in veterinary practices where larger systems are not available but it should be further validated and reference intervals should be determined.

[Analysis of personnel costs after reorganization of intensive care using calculated diagnosis-related groups comparative data. An investigation at the Charité Berlin]

BACKGROUND

In an extensive project intensive care units (ICUs) of the Charité University Hospital were reorganized. The aim of this investigation was to determine if staff costs after this reorganization are financed by modular profits of diagnosis-related groups (DRGs).

METHODS

Staff costs of all non-pediatric intensive care units, including ICUs, intermediate care units and post-anaesthesia care units (PACUs) in the Charité University Hospital were compared with the modular profits of all DRGs of patients older than 14 years in 2005. These DRGs were converted into the German refined DRG (GDRG) system 4.0 from 2006 with calculations based on actual income for medical doctors and nurses in 2006. Due to changed wage agreements for the incomes of physicians in 2006 there was an increase of costs. For the other professional groups an increase in income is expected, which cannot be estimated at present.

RESULTS

The calculation revealed that staff costs of the ICUs at the Charité University Hospital based on a current German mean base rate of 2,836 EUR were 4.2% above the modular profits of the DRGs. As a result of a structural reorganization of the ICUs, the costs of staff could be adapted to the modular profits. Under the conditions of the actual reduced base rate of Berlin of 2,955 EUR the costs and profits were nearly equal. As the financial impact of the reorganization of the ICUs will take full effect in the coming years, it can be anticipated that with an expected base rate of 2,949 EUR in 2010 the intensive care medicine of a University hospital in Germany can become profitable.

DISCUSSION

The spectrum of intensive care medicine at the Charité University Hospital covers the maximum range of operative and non-operative medicine. After an extensive reorganization of the ICUs under the aspect of staff costs, intensive care medicine can become profitable under the 4.0 G-DRG system. With consequent reorganization the cost efficiency of staff can be optimized, particularly in the setting of high-end intensive care medicine.

Barrier function of the gut and multiple organ dysfunction after cardiac surgery

We studied the influence of sequential involvement of the gastrointestinal (GI) tract on the development of multiple organ dysfunction (MOD) after cardiopulmonary bypass (CPB). One hundred and forty-six patients undergoing elective cardiac surgery were included in this prospective observational study. Standardized oral inert-sugar tests (sucrose, lactulose, mannitol, sucralose) were performed before and after CPB in different patients. Enzyme-linked immunosorbent assay of plasma levels of endotoxin core antibodies (EndoCAb) were performed peri-operatively. The functional mucosal surface was calculated from the amount of mannitol absorbed from the GI tract. Lower urine concentrations of absorbed mannitol were observed pre-operatively in patients developing MOD. In binary logistic regression this was an independent parameter. Decreased plasma concentrations of EndoCAb after surgery were seen in every patient, but were more significant in patients developing MOD. A reduced pre-operative functional mucosal surface may predict the early occurrence of MOD after surgery.

High resolution protein electrophoresis of 100 paired canine cerebrospinal fluid and serum

This study was performed to investigate the diagnostic relevance of cerebrospinal fluid (CSF) high resolution electrophoresis. The laboratory technique was applied to 100 paired samples of canine CSF and serum, with paired samples tested during the same analytical run, as recommended in human medicine. Ninety four of the dogs had a neurological disease and 6 healthy dogs served as a control group. A strong linear correlation between CSF total protein concentration and the albumin quota (AQ) was found in the control group and in the inflammatory (infectious or noninfectious), neoplastic, and miscellaneous groups: AQ = 0.015 CSF total protein--0.102, r = 0.990. This correlation suggests that an increased CSF total protein concentration can be an indicator of blood brain barrier dysfunction. The highest median AQ value was found in the aseptic suppurative meningitis group, but no statistical differences were found between this and the other groups. The AQ, calculated with this technique, did not provide any additional information. Moreover, although unexpected, the electrophoretic profiles were not characteristic of any particular disease. In conclusion, this study did not confirm high resolution electrophoresis of paired CSF and serum samples to be a valuable ancillary diagnostic tool for canine neurological diseases.

Stability of selected hematology variables in canine blood kept at room temperature in EDTA for 24 and 48 hours

BACKGROUND

Most hematologic analyses are performed within a short time of blood sampling, but samples collected at the end of a week may have to be stored for up to 2 days. The stability of hematologic constituents is poorly documented.

OBJECTIVE

The objective of this study was to compare the results of RBC, WBC and platelet counts, hemoglobin (Hgb) concentration, and MCV before and after storage of canine blood at room temperature for 24 and 48 hours.

METHODS

One hundred fifty-two K3-EDTA canine blood specimens from 2 veterinary hospitals were analyzed within 4 hours of collection, then 24 and 48 hours later with a Coulter T540 hematology analyzer. Results were compared by Passing-Bablock agreement, difference plots, and according to their classification as normal or abnormal based on reference intervals.

RESULTS

RBC count and Hgb concentration were stable for the duration of the study. Differences in WBC and platelet counts varied with the specimen, independently of the initial value. MCV increased consistently over the 2 days. However, only a few results were misclassified.

CONCLUSION

Whole blood specimens stored for up to 2 days at room temperature are suitable for cell counts and Hgb measurement. However, potential variations have to be known to avoid misinterpretations, especially near the decision limits.

Simultaneous and minimally invasive assessment of muscle tolerance and bioavailability of different volumes of an intramuscular formulation in the same animals1

Evaluation of skeletal muscle tolerance during development of new drug formulations for i.m. use is most often based on terminal methods performed in the target species after slaughtering. The objective of this study was to evaluate the effect of muscle damage on the pharmacokinetic parameters of the drug delivered into the muscle using an alternative, noninvasive method. Phenylbutazone (PBZ) was used as the test article. Six ewes received increasing volumes of a 20% PBZ i.m. formulation, according to a cross-over design, and an i.v. bolus of the same formulation. Serial blood samples were taken, and a pharmacokinetic analysis of the plasma activity of creatine kinase and plasma PBZ concentrations was carried out. The amount of muscle damage after i.m. administration of 2, 4, or 8 mL of PBZ, calculated from the area under the curve of plasma creatine kinase across time was 36, 76, and 178 g for a 70-kg ewe. The corresponding absolute bioavailability of PBZ was 100 +/- 32%, 96 +/- 19%, and 100 +/- 17%, and the maximal PBZ concentrations were 42 +/- 3.4, 74 +/- 8.8, and 119 +/- 18.2 microg/mL. The plasma clearance of PBZ (i.v.) was 4.2 +/- 0.94 mL.kg(-1).h(-1). In conclusion, the absolute bioavailability of PBZ after i.m. administration was not altered by the increased volume of formulation administered despite the overall increase in the extent of muscle damage.

Adverse Haematological Effects of Vinblastine, Prednisolone and Cimetidine Treatment: a Retrospective Study in Fourteen Dogs with Mast Cell Tumours

Vinblastine toxicity is poorly documented in dogs. The aim of this study was to investigate the haematological alterations in dogs treated with vinblastine and prednisolone. Fourteen dogs with mast cell tumours (MCT) were selected on at least one of the following criteria: lymph node infiltration, surgical margin infiltration, grade II MCTs with Ki-67 >10%, and grade III MCTs. Starting 15 days after surgery, the dogs were given vinblastine (2 mg/m2 i.v. four times weekly, then twice monthly for 2 months) and prednisolone (2 mg/kg/day p.o.). An EDTA blood sample was collected weekly for complete blood count (CBC). A total of 98 doses of vinblastine were given to the 14 dogs and 114 CBC were performed. Abnormal haematological findings were observed in 12 CBCs from five dogs, which represent a prevalence of 20% of the total CBCs performed in these animals. The most prevalent abnormal finding was thrombopenia (9/12) most often with grade I toxicity (6/9). In conclusion, the risk of occurrence of adverse haematological effects resulting from vinblastine-prednisolone treatment seems limited in dogs with MCT and it should not be overestimated.

Comparison of measurements of canine plasma creatinine, glucose, proteins, urea, alanine aminotransferase, and alkaline phosphatase obtained with Spotchem SP 4430 and Vitros 250 analyzers

The suitability of the Spotchem 4430 benchtop biochemistry analyzer for canine blood samples was tested for creatinine, glucose, proteins, urea, alkaline phosphatases and alanine aminotransferase. Results obtained from whole blood and corresponding heparin plasma were identical except for proteins which were higher in plasma (n=10). Between series imprecision (n=10) was <5% for substrates and <10% for enzymes. Comparison of results from 100 Li-heparin samples with those measured with a Vitros 250 analyzer showed good correlation (r>0.93). The slopes of the Passing-Bablock's regression ranged from 0.90 to 1.20 and intercepts were low. The mean biases were low, except for creatinine for which the results obtained by Spotchem (Jaffe reaction) were about 20 micromol/L higher than with the Vitros (enzymatic reaction). The results of this study show that the Spotchem analyzer is suitable for use in canine whole blood or plasma when small numbers of tests are to be performed and large analyzers are not available.

Inaccuracy of routine creatinine measurement in canine urine

BACKGROUND

Urine creatinine concentration often is used in ratios such as urine protein:creatinine to compensate for dilution or concentration of spot urine samples.

OBJECTIVE

The purpose of this study was to compare the accuracy of different techniques of urine creatinine measurement currently available for veterinary practitioners.

METHODS

In 104 samples of canine urine diluted 1:20 with distilled water, creatinine concentration was measured using a kinetic Jaffé reaction assay, and an enzymatic technique on an automatic analyzer (Elimat) and 3 benchtop analyzers (Reflovet, Scil; Vitros DT2, Ortho-Clinical Diagnostics; Vettest 8008, IDEXX) used in veterinary practice.

RESULTS

The Jaffé and enzymatic techniques on the Elimat were not significantly different, and their inaccuracy tested with human control urines was <5%. The benchtop analyzers underestimated creatinine concentration, especially at concentrations >2000 mg/L. Inaccuracy was higher with multilayer slide technology systems (Vitros and Vettest) than with the Reflovet system. Results were approximately 25% and 2% lower, respectively, than with the Elimat at urine creatinine concentrations about 2000 mg/L.

CONCLUSION

Inaccuracy in urine creatinine measurements using benchtop analyzers should be taken into account when defining decision thresholds, which should be corrected according to the method used to avoid misinterpretations.

Comparison of plasma/serum urea and creatinine concentrations in the dog: a 5-year retrospective study in a commercial veterinary clinical pathology laboratory

Serum/plasma urea (S/P-urea) and creatinine (S/P-creatinine) concentrations are routinely assayed as indirect markers of glomerular filtration rate and have been reported to be highly correlated. The aim of this study was to evaluate the relationship between the two analytes in a large number of unselected samples submitted to a commercial laboratory. In 4799 pairs of results, the correlation was high (r = 0.795) and was not affected by sex or age. The relationship between the two analytes was best represented by a second-order polynomial equation. However, the dispersion of results was large and there was a high percentage of cases (27.5%) where S/P-urea was increased and S/P-creatinine normal (< or =120 micromol/l for this laboratory), while there was a low percentage of cases where S/P-creatinine (1.6%) was increased and S/P-urea normal (< or =8 mmol/l for this laboratory). The discrepancy between increases in S/P-urea and S/P-creatinine might not only reflect a high incidence of non-renal factors of variation for S/P-urea but also an effect of the size or muscle mass of the dogs on the limit of decision for S/P-creatinine. In dogs with normal S/P-urea, there was a significant effect of the size on the 0.975 quantile of S/P-creatinine, ranging from 106 micromol/l in very small dogs to 133 micromol/l in large and very large dogs. This study shows that isolated increases in S/P-urea could be misleading for the diagnosis of renal diseases and that the reference intervals of S/P-creatinine should be re-evaluated according to breed or muscle mass of dogs.

Splanchnic oxygen transport, hepatic function and gastrointestinal barrier after normothermic cardiopulmonary bypass

BACKGROUND

The effect of non-pulsatile, normothermic cardiopulmonary-bypass (CPB) on the splanchnic blood-flow and oxygen-transport, the hepatic function and the gastrointestinal barrier were observed in a prospective observational study in 31 adults undergoing cardiac valve replacement surgery.

METHODS

The splanchnic (i.e. hepatic) blood-flow (HBF) was measured by the constant infusion of indocyanine-green (ICG) using a hepatic-venous catheter. Liver function was examined by calculation of lactate uptake, ICG extraction and the monoethylglycinexylidide (MEGX) test. A day before and after surgery the gastrioduodenal and intestinal permeability was measured by determination of sucrose and lactulose/mannitol excretion.

RESULTS

Splanchnic blood flow and oxygen delivery did not decrease during and after surgery while splanchnic oxygen consumption (P < 0.0125) and arterial lactate concentrations increased. The splanchnic lactate uptake paralleled the lactate concentration. After but not during CPB an increase of systemic oxygen consumption was observed. The MEGX test values decreased on the first day after surgery. The ICG extraction was attenuated during the operation. The gastroduodenal and the intestinal permeability increased significantly postoperatively (P < 0.002, respectively, P < 0.001). There was no correlation between these findings and the duration of CPB. There was a significant correlation of the intestinal permeability but not of the gastroduodenal permeability between the prior and after surgery values (P < 0.001).

CONCLUSION

Increased oxygen consumption during CPB may indicate an inflammatory reaction due to the pump beginning in the splanchnic area or a redistribution of the splanchinc blood flow during the CPB. Normothermic CPB does not lead to a significant or prolonged reduction of liver function. Normothermic CPB causes an increase of gastrointestinal permeability. The intestinal barrier function prior to surgery was accountable for the degree of loss of intestinal barrier function following surgery.

Comparison of whole blood and plasma potassium concentrations in dogs using the Reflovet system

BACKGROUND

The Reflovet system is designed for chemical analysis of whole blood. However, plasma or serum is recommended for potassium analysis because of possible interference from RBC potassium. Because RBC potassium concentration is low in most canine erythrocytes, however, there should be little or no interference.

OBJECTIVE

The objective of this study was to compare potassium results obtained in whole blood and in plasma from dogs using the Reflovet system.

METHODS

Blood samples were collected from 104 dogs into lithium-heparin tubes. The potassium concentration was measured in whole blood, and subsequently the PCV was measured. Samples were centrifuged and the potassium concentration was measured in plasma. Comparisons were made using Deming's regression and Bland-Altman difference plots.

RESULTS

There was very good correlation between results of potassium measurements in whole blood and plasma (r = 0.93). Potassium values were moderately lower in whole blood: Potassium(blood) = 0.912 x Potassium(plasma)+ 0.119. Hemolysis had a negligible effect on the results, but the difference increased with the PCV value. In more than 90% of samples, the difference between the 2 measurements was <or= 0.3 mmol/L.

CONCLUSION

There is only a negligible difference in most cases between potassium values in canine plasma and whole blood using the Reflovet system.

Creatinine in the Dog: A Review

Creatinine is the analyte most frequently measured in human and veterinary clinical chemistry laboratories as an indirect measure of glomerular filtration rate (GFR). Although creatinine metabolism and the difficulties of creatinine measurement have been reviewed in human medicine, similar reviews are lacking in veterinary medicine. The aim of this review is to summarize information and data about creatinine metabolism, measurement, and diagnostic significance in the dog. Plasma creatinine originates from the degradation of creatine and creatine phosphate, which are present mainly in muscle and in food. Creatinine is cleared by glomerular filtration with negligible renal secretion and extrarenal metabolism, and its clearance is a good estimate of GFR. Plasma and urine creatinine measurements are based on the nonspecific Jaffé reaction or specific enzymatic reactions; lack of assay accuracy precludes proper interlaboratory comparison of results. Preanalytical factors such as age and breed can have an impact on plasma creatinine (P-creatinine) concentration, while many intraindividual factors of variation have little effect. Dehydration and drugs mainly affect P-creatinine concentration in dogs by decreasing GFR. P-creatinine is increased in renal failure, whatever its cause, and correlates with a decrease in GFR according to a curvilinear relationship, such that P-creatinine is insensitive for detecting moderate decreases of GFR or for monitoring progression of GFR in dogs with severely reduced kidney function. Low sensitivity can be obviated by determining endogenous or exogenous clearance rates of creatinine. A technique for determining plasma clearance following IV bolus injection of exogenous creatinine and subsequent serial measurement of P-creatinine does not require urine collection and with additional studies may become an established technique for creatinine clearance in dogs.

Assessment of a pyrogallol red technique for total protein measurement in the cerebrospinal fluid of dogs

The measurement of protein concentration in the cerebrospinal fluid is a basic analytical method in neurology. In this study, a pyrogallol red technique using a human albumin calibrator previously validated in human medicine was tested for canine samples, and the results were compared with those obtained using urine test strips. Pyrogallol red significantly (P<0.05) but moderately underestimated purified dog albumin and globulins. The imprecision of the technique was low: intra- and between-series coefficients of variation were 1.6 and 4.3 per cent at protein concentrations of about 0.3 g/litre. Over 49 samples, there was good agreement between the pyrogallol red and test strip results (r=0.63), especially for low and high protein concentrations, but misclassifications were observed with '+' test strip readings.

Comparison of the techniques of evaluation of urine dilution/concentration in the dog

The objective of this study was to evaluate the quality of the measurement of dog urine dilution/concentration by comparing osmolality with three methods of specific gravity (USG) measurement, i.e. weighing, refractometry and test strips. In unselected urine samples from 182 dogs there was a better agreement between osmolality and USG determination by refractometry (r = 0.92) than by weighing (r = 0.82) or by test strips (r = 0.27). There was an almost linear relationship between osmolality and USG: osmolality (mOsm/kg) = 36646(34318/38974) x (USGref - 1) + 25(-39/88); calculated osmolality differed from measured osmolality by more than 500 mOsm/kg in only 8 of 181 samples. There was a good agreement between USG determination by weighing and refractometry: USGref = 1.000(0.905/1.095) x USGweighing - 0.0004(-0.0019/0.0027), with a moderate bias. Only 12% of the differences between the two methods exceeded 0.010. Test strip assessment of USG was unreliable because of systematic underestimation and should not be used for dog urine. Refractometry is the best technique for routine evaluation of urine concentration/dilution when osmometry is not available.

The accuracy of the i-STAT portable analyser for measuring blood gases and pH in whole-blood samples from dogs

To assess the suitability of the i-STAT portable analyser for use by non-laboratory personnel, we measured blood gases and pH in venous blood samples from 100 dogs. Deming's regression and bias plots were used to compare i-STAT results with those obtained by laboratory professionals using two different autocalibrated benchtop analysers. Overall accuracy of the portable analyser proved excellent for pH, pO(2), and pCO(2) (r=0.978, 0.968 and 0.997, respectively), with Deming's regression slopes close to 1.00 (0.96, 0.97 and 1.08 for pH, pO(2), and pCO(2), respectively) and intercepts close to zero (0.28, 0.47 kPa and 0.46 kPa for pH, pO(2), and pCO(2), respectively). The accuracy of the i-STAT was also satisfactory for calculated parameters: bicarbonates, total CO(2), base excess and oxygen saturation. Our findings show this portable analyser to be a valid substitute for expensive benchtop analysers in situations requiring mobility, or when small numbers of tests are to be performed by users not specialized in laboratory techniques.

Exercise does not induce major changes in plasma muscle enzymes, creatinine, glucose and total proteins concentrations in untrained beagle dogs

Changes in plasma creatinine (Pl-Creat), glucose, total proteins (Pl-TP), creatine kinase (Pl-CK), lactate dehydrogenase, aspartate aminotransferase and packed cell volume were evaluated in untrained Beagle dogs before, during and after a 60 min race at an average speed of 9 km/h. There was no major effect of exercise on those parameters except, when phases are compared, a slight increase of Pl-TP during exercise (max. + 6.4%), a moderate but after exercise (delayed increase of Pl-CK max. + 245%) and a slight decrease of Pl-Creat after exercise (max. -9.6%). It was therefore concluded that strenuous exercise in sedentary dogs did not induce major variations in any of routine plasma variables measured and would not lead to clinically relevant misinterpretation. However, for Pl-CK, the interpretation of repeated measures may be misleading if two samples are collected in the same animal before and after exercise.

Plasma exogenous creatinine clearance test in dogs: comparison with other methods and proposed limited sampling strategy

Plasma clearance of creatinine was evaluated for assessment of glomerular filtration rate (GFR) in dogs. In 6 healthy dogs (Experiment 1), we determined 24-hour urine clearance of endogenous creatinine, plasma, and urine clearances of exogenous creatinine administered at 40, 80, and 160 mg/kg in a crossover design (linearity study), plasma iothalamate clearance, and plasma and urine clearances of 14C-inulin. In Experiment 2, plasma creatinine and iothalamate clearances were compared, and a linearity study was performed as for Experiment 1 in 6 dogs with surgically induced renal impairment. Experiment 3 compared plasma creatinine clearance with plasma iothalamate clearance before and 3 weeks after induction of moderate renal impairment in 6 dogs. Plasma creatinine clearances were calculated by both noncompartmental and compartmental analyses. In Experiment 1, plasma inulin clearance was higher (P < .001) than other clearance values. Plasma creatinine clearances at the 3 dose rates did not differ from urine inulin clearance and each other. In Experiment 2, plasma creatinine clearances were about 14% lower than plasma iothalamate clearance (P < .05). In Experiment 3, decreases in GFR assessed by plasma clearances of iothalamate and creatinine were similar. Renal failure decreased the daily endogenous input rate of creatinine by 25%. Limiting sampling strategies for optimizing GFR calculation were proposed, allowing an error lower than 6.5% with 4 blood samples. These results suggest that determination of plasma creatinine clearance by a noncompartmental approach offers a reliable, inexpensive, rapid, and convenient means of estimating GFR in routine practice.

Plasma fibrinogen measurement in the horse: comparison of Millar's technique with a chronometric technique and the QBC-Vet Autoreader

Plasma fibrinogen is widely used in horse practice as an unspecific positive marker of inflammatory diseases; it is also lowered in disseminated intravascular coagulation. Three fibrinogen measurement methods--Millar's heat-denaturation in a microhaematocrit tube, automated reader for heat-denaturation, and chronometric measurement of clot formation after addition of excess thrombin-were compared by means of Passing-Bablock's regression and Bland-Altman difference plots, in blood plasma of 30 clinically healthy and 57 diseased horses. Correlations between the three techniques were excellent (r >0.92). The two heat-denaturation techniques correlated very closely up to 6 g l(-1), above which the results obtained by Millar's technique started to fall below those obtained by the automatic reader. There was proportional bias between Millar's technique and the chronometric technique, with the latter producing results some 30% lower, indicating that reference intervals and decision limits should be adapted accordingly.

Differential effects of phenobarbital on the constitutive and inducible expression of P450 2B and 3A subfamilies in sheep tissues

The activity and expression of cytochromes P450 were determined in liver, kidneys, lungs, duodenum, jejunum, ileum, and caecum of adult Lacaune sheep. High expression of total P450, benzphetamine and erythromycin demethylase activities, and P450 2B isoforms, as two distinct proteins that were detected and called P4502 Bm and P4502 Bx, was found in the lungs (in addition to liver). By contrast, the P450 3A subfamily was only expressed in liver and duodenal mucosa of untreated sheep. Phenobarbital (PB) treatment led to significant increases in all measured hepatic parameters and in total P450 of each investigated organ with the exception of ileum and caecum. Benzphetamine demethylase activity increased in liver and kidneys, correlating with the expression of the two P450 2B proteins, which were also induced in duodenum and ileum. By contrast, benzphetamine demethylase activity and expression of the P450 2B isoforms in lungs were unchanged by PB treatment. Erythromycin demethylation activity and P450 3A subfamily expression was increased only in liver of PB-treated sheep.