The formation of Ca++-dependent complexes of platelet membrane glycoproteins IIb and IIIa in solution as determined by crossed immunoelectrophoresis

Triton X-100 soluble proteins from 125I-labeled human platelets were studied by crossed immunoelectrophoresis employing a multispecific rabbit antibody raised against whole normal platelets. Emphasis was placed upon an analysis of immunoprecipitates containing 125I-labeled major membrane glycoproteins, and in particular, a prominent immunoprecipitate containing a glycoprotein antigen (s) previously designated as protein 16. SDS-polyacrylamide gel electrophoresis of protein 16 precipitated by a monospecific alloantibody. IgG L . . . , confirmed the presence of both glycoproteins IIb and IIIa. 125I-IgG L . . . , at concentration below that capable of precipitating protein 16 by itself, bound specifically to the precipitate containing protein 16 produced by the multispecific rabbit antibody. No other precipitates formed by the rabbit antibody contained either glycoprotein IIb or IIIa. When platelet proteins, incubated with optimum concentrations of ethylenediamine tetraacetic acid (EDTA) or ethyleneglycol bis (B- aminoethylether) NN1-tetraacetic acid (EGTA), were electrophoresed against the rabbit antibody, previously unobserved immunoprecipitates that contained either free glycoprotein IIb or free glycoprotein IIIa were detected. Upon readdition of excess Ca++, but not Mg++, to the same protein samples, a single immunoprecipitate containing both glycoproteins was once again observed. It is thus demonstrated that glycoproteins IIb and IIIa can form Ca++-dependent complexes (protein 16) in Triton X-100 extracts of normal platelets. The potential significance of the reversible association of these glycoproteins to normal platelet function is discussed.     

Long-term follow-up patients with leukemia receiving platelet transfusions: identification of a large group of patients who do not become alloimmunized

Alloimmunization is the major complication of platelet transfusion therapy in patients with acute leukemia. To evaluate whether alloimmunization continues to be a long-term problem in patients surviving induction therapy, 114 patients with acute nonlymphocytic leukemia (ANLL) who survived more than 6 mo and who received multiple courses of chemotherapy and abundant platelet transfusions were studied. Clinical response to random donor platelets and lymphocytotoxic antibody (LCTAb) were measured pretreatment and serially throughout the study period. Fourteen patients (12%) were alloimmunized upon admission, 34 (30%) patients became alloimmunized during remission induction therapy, and 66 (58%) patients did not become alloimmunized during that period. Sixty-one of these 66 patients (92%) never became alloimmunized and responded to random donor platelets during their subsequent course despite the fact they received multiple further platelet transfusions, whereas the alloimmunized patients tended to remain alloimmunized for their entire clinical course. There was no difference in age or sex between groups, and prognostic factors predicting alloimmunization could not be detected. In greater than 90% of patients not alloimmunized at admission, the presence or absence of LCTAb after induction predicts later alloantibody production. This information can be used to plan the type of platelet transfusions (HLA-matched or random donor) needed for subsequent maintenance and induction therapy. It may also help to identify a group of patients to whom more aggressive maintenance chemotherapy may be more safely administered.     

Predicting late-onset growth abnormalities using growth velocity between trimesters

Objectives.?To determine whether growth velocity parameters derived from routine prenatal ultrasound measurements at first, second and third trimester can identify normal growth at term as well as late-onset growth abnormalities.

Material and methods.?Longitudinal study of fetal growth in normal singleton pregnancies with three normal ultrasound examinations and delivered at term. Fetuses were classified into 3 groups (?<?10th percentile, 10–90th percentile, >?90th percentile) based on birth weight. Multiple regression on birth weight classification was used to build up a prediction equation of fetal growth potential (FGP) based on fetal biometry and fetal growth velocity parameters between ultrasound examinations. Best cut-off value for FGP predicting growth restriction and macrosomia were defined.

Results.?356 pregnancies were included. Fetal biometry growth velocities between examinations were calculated for all measurements. Using best cut-off values, the estimated sensitivity, specificity and odds ratio were: 60% [44;74], 91%[89;92] and 14.55 [6.30;33.98] and 53% [36;69], 89%[88;91] and 10 [4.27;23.49] for the prediction of growth restriction and macrosomia, respectively.

Discussion.?Fetal growth potential can be derived and calculated from standard ultrasound measurements. It can improve identification of these fetuses at risk for late-onset growth abnormalities and their related morbidity.     

Proton spectroscopic imaging (Dixon method) of the liver: clinical utility

The contribution of proton spectroscopic (PS) imaging to magnetic resonance (MR) imaging of the liver was assessed at 0.5 T in 55 patients with known or suspected hepatic malignancy. PS images were compared subjectively with T1- and T2-weighted spin-echo (SE) images for hepatic lesion detection and conspicuity. For hepatic metastases (n = 27), PS images were equal to T1-weighted images in lesion detection in 17 patients but showed fewer lesions in five patients and false-negative results in two. When compared with T2-weighted images, PS images depicted more lesions in six patients, an equal number of lesions in 18, and fewer lesions in two. Hepatomas (n = 8) were detected with each sequence in all patients. Hepatomas were often more conspicuous on PS images than on T2-weighted images; they were of equal conspicuity on PS and T1-weighted images in most cases. Whereas fatty infiltration (n = 16) appeared on PS images as areas of low signal intensity similar to that of paraspinal muscle, it produced no detectable abnormality on either T1- or T2-weighted images. PS imaging is inferior to T1-weighted SE imaging in the detection of hepatic metastases. The major role of PS imaging at intermediate field strength is to differentiate focal fatty infiltration from hepatic metastases.     

Percutaneous cholecystostomy: an alternative to surgical cholecystostomy for acute cholecystitis?

Emergency percutaneous cholecystostomy was successfully performed in 39 of 40 attempted procedures in 37 hospitalized patients with possible acute cholecystitis. All cholecystostomies were performed with ultrasound guidance and preferentially with the transhepatic route, and all but four were performed at the patient's bedside. The patients had been hospitalized an average of 27 days before the procedure. Twenty-two of the 37 patients (59%) eventually died during hospitalization because of other medical or surgical problems. Only minor complications related to percutaneous cholecystostomy placement occurred in this series: catheter dislodgment without sequelae (n = 2) and significant abdominal pain (n = 2). Technical problems included guide-wire buckling during catheter insertion (n = 1) and failed attempted cholecystostomy (n = 1). Percutaneous cholecystostomy is a safe alternative to surgical cholecystostomy in the treatment of patients suspected of having acute cholecystitis.     

US-guided percutaneous biopsy: use of a screw biopsy stylet to aid needle detection

Insertion of a screw biopsy stylet into a thin-walled biopsy needle greatly enhances detection of the needle during ultrasound-guided percutaneous biopsy. This technique is helpful when precise needle-tip localization is needed for biopsies of small lesions.     

Outpatient metrizamide myelography: prospective evaluation of safety and cost effectiveness

A group of 228 consecutive patients undergoing metrizamide myelography was prospectively evaluated for postprocedure symptoms. The observed prevalence of these symptoms concurs with previously reported inpatient studies, with the most common sequelae being exacerbation or onset of spine or extremity pain, headache, nausea, and paresthesia. Limitation of administered dose of metrizamide in lumbar myelography may slightly reduce the occurrence of common symptoms, but withdrawal of contrast medium at the completion of examination had no impact on their occurrence. There was a higher occurrence of paresthesia in cervical myelography, but otherwise there was no significant difference in symptoms between cervical and lumbar studies. Outpatient metrizamide myelography can be performed with relative safety with the potential for significant cost savings.