Compact analyzers suited to near-patient testing estimate hematocrit by measuring the conductivity of undiluted blood. We evaluated the accuracy of hematocrit determination of one such analyzer (Instrumentation Laboratory BGE analyzer) against an automated cell counter (EPC) and packed cell volume (PCV) microhematocrit. When specimens (n = 34) from outpatient and ward patients were analyzed with all three methods, the BGE analyzer correlated well with both EPC and PCV hematocrit determinations (BGE = 1.00 PCV + 0.3%, S(y)/x = 2.0%), suggesting that all three methods are similar in performance for most patients. However, a patient with increased plasma osmolality showed significant decreases in BGE and PCV hematocrits relative to the EPC method. The differences in hematocrit measurements could be reproduced by adding solutes to blood in vitro or by modifying the plasma osmolality of rats in vivo. Samples from patients undergoing cardiac surgery, whose blood had large changes in protein concentration, showed discrepancies between hematocrits by conductivity and other methods; similar effects could be produced by changes in protein concentration or in vitro addition of polyethylene glycol. We conclude that conductivity measurements provide accurate hematocrit results for physiologically normal subjects but not for some intensive-care and surgical patients.

In search for a luminol with very high output of light, 20 different luminol samples were tested for their ability to enhance the chemiluminescence reaction in phorbol myristate acetate activated human neutrophils. We found that the majority of luminols tested (17 samples) gave almost the same light output from neutrophils, and that the major part of the activity was from an intracellular origin. Owing to the fact that three isoluminol samples were unable to monitor respiratory burst activity taking place intracellularly, a very low level of chemiluminescence was obtained with these samples. Their light output was, however, greatly increased when horseradish peroxidase or myeloperoxidase was added, showing that the light-generating reaction with isoluminol as well as with luminol is peroxidase-dependent. The fact that isoluminol could also use myeloperoxidase as amplifying peroxidase, suggests that that the lack of measurable intracellular activity in the presence of isoluminol is somehow related to a limited or restricted diffusion of the molecule to intracellular sites. The isoluminol system constitutes a sensitive system for measuring release of oxygen metabolites from phagocytic cells.

Accession no.X06683 Cu-Zn superoxide dismutase (EC 1.15.1.1) is a eukaryotic cytoplasmic enzyme involved in the antioxidant defense against the toxic effects of superoxide anion-induced cellular damage (1). We have isolated cDNA clones from a murine SWR/J liver cDNA library (2) using the human cDNA clone pS61-10 as a heterologous probe (3). The nucleotide and deduced amino acid sequence of one of these clones containing the entire coding region is shown below. The murine enzyme is coded for by 459 nt after ATG followed by a single stop codon. The deduced amino acid sequence exhibits 83.7% identity to the human enzyme (3) and 96.7% identity to the rat enzyme (4). The 3-non-coding end following TAA is 66 nt in length and contains an uncommon polyadenylation signal, ATTAAA, 16 nt upstream of the poly(A) tail. This clone hybridizes to a single band of RNA isolated from mouse liver with a molecular size between 0.5-0.6 kb.

We measured parathyrin (parathyroid hormone)-related peptide (PTHRP) in plasma by three region-specific RIAs and compared them with an established two-site immunoradiometric assay (IRMA) of PTHRP1-86 in samples from control subjects and from patients with primary hyperparathyroidism (PH) and humoral hypercalcemia of malignancy (HHM). The two direct RIAs of PTHRP1-34 and PTHRP37-67 were specific for regions 9-18 and 52-61, respectively. In the extraction RIA of PTHRP1-34 we used an affinity gel containing a monoclonal antibody specific for the 17-27 sequence; cross-reacting PTHRP species eluted from the gel were assayed by the RIA of PTHRP1-34. PTHRP1-86 plasma concentrations by IRMA were less than 0.23 pmol/L in control subjects and patients with PH, and were significantly increased in patients with HHM (mean 6.1 pmol/L, P less than 0.001). In contrast, plasma PTHRP1-34 concentrations were not significantly different in the three groups; in HHM patients, the mean was 190 pmol/L. Plasma PTHRP37-67 concentrations were similar in control and PH groups and, although significantly increased in HHM patients (mean 440 pmol/L, P less than 0.002), showed poor diagnostic discrimination. PTHRP1-34 concentrations after affinity extraction of plasma were also significantly higher in HHM patients (mean 10.7 pmol/L, P less than 0.001), but showed incomplete diagnostic discrimination. We conclude that the diagnostic utility of the direct RIAs for quantifying PTHRP is markedly inferior to the IRMA of PTHRP1-86.

No abstract