Electrocardiographic parameters of normal alpacas (Lama pacos).

The electrocardiographic parameters of 40 healthy alpacas (Lama pacos) were recorded with a base-apex lead system to establish the normal resting electrocardiographic parameters in this species. The following parameters were measured: heart rate and rhythm, QRS and T morphology, ST segment position, P amplitude and duration, QRS duration and PQ and QT intervals. The heart rate varied between 50 and 110 bpm, with a mean (sd) of 80 (17.8) bpm, and no significant differences were observed between males and females or between alpacas of different ages. Sinus arrhythmia was observed in 35 of the animals, and a regular sinus rhythm was recorded in the other five. The QRS morphology was variable, with an 'rS' pattern observed in 29 animals, 'RS' in six, 'Rs' in three and 'QS' in the other two. A variable morphology was also observed for the T wave, which was positive in 27 animals, negative in seven and biphasic in the other six. All the electrocardiographic parameters were normally distributed and no significant differences were observed between the sexes, except that the amplitude of the P wave was higher in males. The PQ interval was significantly shorter in animals less than six months old.

Platelet crossmatches of single-donor platelet concentrates using a latex agglutination assay.

A latex agglutination assay was evaluated for the purpose of identifying compatible platelet donors for alloimmunized recipients. Assay reagents were prepared by adsorbing detergent-solubilized, donor-specific platelets to polystyrene latex beads. Semiquantitative results for up to 30 donors can be completed in less than 1 hour. These reagents retained their immunoreactivity for at least 3.5 months. A retrospective study has established the assay's upper limit of compatibility. The prospective study evaluated transfusions to a group of multiply transfused patients. Part I evaluated 143 crossmatched, single-donor platelet transfusions given to 50 patients. In 96 percent of the cases, a positive crossmatch was associated with an unsuccessful transfusion outcome; in 84 percent of the transfusions, a negative crossmatch predicted a satisfactory platelet increment. The overall predictability, sensitivity, and specificity were 87, 62, and 99 percent, respectively. Part II evaluated 105 transfusions given to the 43 patients (of 50) in whom no incidence of fever, sepsis, or bleeding could be documented. A positive crossmatch was 96-percent efficient in predicting an unsuccessful transfusion, whereas a negative crossmatch was associated with an adequate platelet increment following 89 percent of the transfusions. The overall predictability was 91 percent, the sensitivity was 72 percent, and the specificity was 99 percent. Within-run and between-run variations were 6.3 and 6.2 percent, respectively. These results demonstrate that detergent-solubilized platelet antigens, immobilized on latex particles, can be used in a cost-effective crossmatching procedure.

Plasma fibronectin values in patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex.

The authors studied the circulating fibronectin concentrations in the plasma of 24 patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) and of 74 age- and sex-matched healthy blood donors. They adapted a commercially available turbidimetric immunoassay for use with a centrifugal analyzer. The assay showed within-run precision of 2.1%, 2.3%, 1.8%, and 1.1%, and an accuracy of 90%, 99%, 98%, and 98% at fibronectin concentrations of 126 mg/L, 200 mg/L, 293 mg/L, and 317 mg/L, respectively. Between-run precision was 5%, 3%, and 2% for 66 mg/L, 218 mg/L, and 283 mg/L concentrations, respectively. Plasma fibronectin values obtained from the healthy blood donors were in good agreement with those values reported by other investigators using various methods. No significant differences between the plasma fibronectin values of the patient population (mean +/- 2 SD = 294 mg/L +/- 110 mg/L) and of the control group (mean +/- 2 SD = 311 mg/L +/- 130 mg/L) were noted. The authors conclude that the measurement of fibronectin concentrations in patients with AIDS or ARC does not contribute significantly to the diagnosis and therapeutic management of these patients.

An enzyme-linked immunosorbent assay for the detection of platelet antibodies using detergent-solubilized platelets immobilized on nitrocellulose discs.

A method is detailed for the solubilization of human platelets using a dialyzable detergent, decanoyl-N-methylglucamide (Mega-10). At a detergent/protein ratio of 1:12, the efficiency of solubilization was 27%. This platelet lysate (PLy) was then bound to nitrocellulose (NC) discs to assay retention of the native immunological functions of the platelet membrane antigens. Using alkaline phosphatase-coupled anti-IgG, the major platelet membrane glycoproteins GPIb, GPIIb, and GPIIb/IIIa were detectable with as little as 20 ng of monoclonal antibody. Antisera to the class I histocompatibility antigens HLA-A1, B7, B8, the PlA1 allodeterminant, and serum from multiply transfused, alloimmunized patients were reactive even after 100 days storage of the discs at 4 degrees C, and with as little as 1.0 micrograms of NC-bound PLy. The binding of the same antisera to intact, immobilized platelets as well as specific complement-mediated lymphocytotoxicity was also inhibited by PLy. PLy from HLA-A3- or B44-positive donors, however, did not inhibit cytotoxicity of lymphocytes expressing either antigen using several different antisera. Our results indicate that Mega-10 is an excellent solubilizing agent for the immunological study of platelet membranes. The fact that clinically relevant platelet membrane antigens are preserved, immunologically reactive, and stable over long periods of storage, makes this assay amenable to a routine crossmatching procedure for platelet transfusions.