Studies of the Pelger-Huët anomaly in foxhounds.

An inbred family of foxhounds with four members expressing the Pelger-Huët (P-H) anomaly is described. The disease-free status of all P-H affected dogs suggests a benign disorder, although review of breeding records indicated a lower percentage of pups weaned (63%) by P-H females compared with the percentage of pups weaned (81%) by outcrossed females throughout the foxhound colony. Light-microscopic examination of blood films from affected dogs revealed 50--67% neutrophils with round, oval, or bean-shaped nuclei and rarely (0.5%) segmented nuclei. Neutrophils examined by electron microscopy showed the nuclei to have a fine nuclear cleft and condensed chromatin and the cytoplasm to have mature heterochromatic granulation. Local P-H neutrophil mobilization through a standard skin abrasion into a chamber containing autologous serum was impaired at all time periods evaluated (1, 4, 8, and 24 hours) compared with the neutrophil mobilization by normal dogs. Antibody response to sheep erythrocyte immunization was also impaired. In vitro reactivity of normal and P-H lymphocytes stimulated by pokeweed mitogen was depressed when lymphocytes were cultured in plasma from a P-H dog but not when cultured in plasma from a normal dog. Vigorous blastogenic responses to phytohemagglutinin by normal and P-H lymphocytes cultured in P-H or normal plasma suggest the presence of a factor(s) in the P-H plasma which interferes with B-lymphocyte reactivity.     

Impaired neutrophil chemotaxis in Pelger-Huët anomaly.

A family has previously been described in which four members with Pelger-Huët (P-H) anomaly suffered from recurrent attacks of abdominal pain and fever, while one member, whose polymorphonuclear leucocytes (PMNs) were also hyposegmented, was asymptomatic. We studied chemotaxis, chemokinesis and spontaneous locomotion of PMNs in the three surviving symptomatic sisters, in their asymptomatic brother and in two asymptomatic members of another family with P-H anomaly. The spontaneous migration of the PMNs of the three sisters was significantly slower both under agarose and in a membrane filter than that of the PMNs of the asymptomatic patients with P-H anomaly. Chemotactic and chemokinetic locomotion of the PMNs of the symptomatic sisters was also slow. Our results suggests that the impaired chemotaxis was due to a defect in the intrinsic locomotor capacity of PMNs rather than in their deformability or their responsiveness to the chemotactic stimulus.     

Validation of an immunoassay for measurement of plasma total homocysteine

Hyperhomocysteinemia is an evolving cardiovascular risk factor. It is imperative that a simple, precise, and accurate assay be available in the clinical laboratory. The aim of this study was to evaluate an automated fluorescence polarization immunoassay for homocysteine. The assay had excellent precision at normal and high levels (intra-assay and interassay coefficients of variation < 5%). The method was linear from 0.24 to 50 mumol/L and displayed good correlation with a high-performance liquid chromatography (HPLC) method. There was no significant interference detectable in icteric and hyperlipidemic samples, but hemolysis resulted in a significant negative bias. While homocysteine levels were not increased in smokers, patients with renal failure had significantly higher levels compared with control subjects. This automated assay requires no sample preparation, displays excellent precision, shows good correlation with HPLC, and, thus, is favored over HPLC for use in the clinical laboratory. The main indications for measuring plasma homocysteine levels will be in the early diagnosis of cobalamin deficiency, patients with cardiovascular disease and few or no established risk factors, and patients with unexplained venous thromboembolic disease.     

Reevaluation of the radiographic method for measurement of total lung capacity

To clarify whether the radiographic estimate of total lung capacity (TLC) using the method of Barnhard et al., as modified by Loyd et al., yields accurate values, we measured TLC in 20 young healthy subjects with the above technique (Vb). We compared it to the more sophisticated radiologic method of Pierce et al. (Vp) and to plethysmographic measurements (Vbox). Plethysmographic results, 7.38 +/- 0.94 l (mean +/- SD) or 101.7% of predicted, were significantly higher than Vb (mean difference 0.53 +/- 0.68 l; p less than 0.005 by paired t test), but were not significantly different from Vp (mean difference 0.13 +/- 0.52 l). Based on these and previous data, we conclude that the Pierce et al. approach yields more accurate results than the Barnhard and Loyd method, although individual data, in both methods, should be interpreted cautiously.     

Efficacy of using total bilirubin values as a guide for screening direct bilirubin requests

Two divergent laboratory approaches to the determination of direct bilirubin were assessed. The first approach, assaying direct bilirubin (DB) on all total bilirubin (TB) requests regardless of TB values, resulted in a true negative rate (normal TB level less than 1.0 mg/dL [less than 17 mumol/L], and DB level, less than 0.4 mg/dL [less than 6.8 mumol/L]) of 98.7% (984/997 specimens) and a low false negative (normal TB level, abnormal DB level) rate of 1.3% (13 of 997). The second approach, assaying DB on physician request and only if the TB level was greater than or equal to 1.0 mg/dL (1.7 mumol/L), resulted in a true negative rate (normal TB level, no liver disease) of 87.7% (150%) of 171 patients) and a relatively low false negative rate (normal TB level, liver disease) of 12.3% (21 of 171) patients. Medical chart review revealed that, with either approach, none of the patients with false negative results with hepatobiliary disease would have been missed clinically, even if the DB assay had not been done. It is possible to screen DB requests using a TB of 1.0 mg/dL (17 mumol/L) as a means to determine whether DB should be assayed.     

An automated method for serum bilirubin determination

A method for the determination of both direct and indirect serum bilirubin on the AutoAnalyzer is described which has a number of advantages over the automated method that is currently recommended. It gives total bilirubin results which are similar to those obtained with the equivalent manual method and direct bilirubin results which are usually about 10% lower.     

Evaluation of the refractometric method for the determination of total protein in avian plasma or serum

Serum total protein concentrations in pigeon blood determined with the biuret method (TPB-se) were compared with total protein concentrations in plasma (TPR-pl) and serum (TPR-se) obtained by estimation from refractive index. The refractometric method consistently yielded higher values (P<0.01). A significant correlation between TPB-se and TPR-se was found (r = 0.62) but not between TPss-se and TPR-pl. The calculated regression equation TPR-se = 0.69 TPB-se + 16 was considered to have no practical value, because the correlation coefficient was low (r = 0.62). The refractometric method for determination of TP in pigeon blood is not recommended.     

Plasma homocysteine measurement: a study of pre-analytical variation factors for conditions for total plasma homocysteine concentration

An increase in homocysteine, a sulphur amino acid, is nowdays considered as a risk factor for cardiovascular diseases, and is independent of other risk factors. Reference range for total plasma homocysteine level in adults is usually 5-15 mmol/l. Hyperhomocysteinemia is defined as a fasting total plasma homocysteine level > 15 mmol/l. There may be also graded increased risks for subjects with homocysteinemia from 10 to 15 mmol/l. However, no threshold has been defined, partly because of the lack of standardization in pre-analytical and analytical steps. The aim of the present work was to evaluate three pre-analytical parameters on plasma homocysteine levels: i) the influence of three anticoagulants (EDTA, sodium citrate and lithium heparin); ii) the delay period of blood sample on ice before centrifugation; and iii) the advantages of strong acidic citrate at room temperature. The mean concentrations of total plasma homocysteine were different in function of the anticoagulant. These differences (EDTA minus lithium heparin or EDTA minus sodium citrate) were less than 10% however the used methods and could explain the good correlation between the results. However we recommend to keep the anticoagulant constant in the same study. When EDTA blood samples were immediately put on crushed ice, the maximum delay period before centrifugation could reach 4 hours. If ice is unavailable, strong acidic citrate at room temperature is a good alternative until for 4 hours.