Application of Color Transformation Techniques in Pediatric Spinal Cord MR Images: Typically Developing and Spinal Cord Injury Population

The purpose of this study was to evaluate an improved and reliable visualization method for pediatric spinal cord MR images in healthy subjects and patients with spinal cord injury (SCI). A total of 15 pediatric volunteers (10 healthy subjects and 5 subjects with cervical SCI) with a mean age of 11.41 years (range 8–16 years) were recruited and scanned using a 3.0T Siemens Verio MR scanner. T2-weighted axial images were acquired covering entire cervical spinal cord level C1 to C7. These gray-scale images were then converted to color images by using five different techniques including hue-saturation-value (HSV), rainbow, red-green-blue (RGB), and two enhanced RGB techniques using automated contrast stretching and intensity inhomogeneity correction. Performance of these techniques was scored visually by two neuroradiologists within three selected cervical spinal cord intervertebral disk levels (C2-C3, C4-C5, and C6-C7) and quantified using signal to noise ratio (SNR) and contrast to noise ratio (CNR). Qualitative and quantitative evaluation of the color images shows consistent improvement across all the healthy and SCI subjects over conventional gray-scale T2-weighted gradient echo (GRE) images. Inter-observer reliability test showed moderate to strong intra-class correlation (ICC) coefficients in the proposed techniques (ICC?>?0.73). The results suggest that the color images could be used for quantification and enhanced visualization of the spinal cord structures in addition to the conventional gray-scale images. This would immensely help towards improved delineation of the gray/white and CSF structures and further aid towards accurate manual or automatic drawings of region of interests (ROIs).     

University of Miami Division of Clinical Pharmacology therapeutic rounds: drug-induced hyperkalemia

Drug-induced hyperkalemia is an important but often overlooked problem encountered commonly in clinical practice. It may occur in the ambulatory as well as the impatient setting. Every evaluation of a hyperkalemic patient should include a careful review of medications to determine if a drug capable of causing or aggravating hyperkalemia is present. Medications generally produce hyperkalemia either by causing redistribution of potassium (beta2 -adrenergic blockers, succinylcholine, digitalis overdose, hypertonic mannitol) or by impairing renal potassium excretion. Drugs cause impaired renal potassium excretion by (1) interfering with the production and/or secretion of aldosterone (nonsterodial anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, angiotensin-II receptor antagonists, heparin, cyclosporine, and FK 506) or (2) blocking the kaliuretic effects of aldosterone (potassium-sparing diuretics, trimethoprim, pentamidine, and nefamostat mesilate). Because severe renal insufficeiency is generally required to cause hyperkalemia, an elevated serum potassium concentration in a patient with mild-to-moderate renal failure should not be ascribed to renal failure alone. A careful search for "hidden" potassium loads and for causes of impaired tubular secretion of potassium (including drugs) is necessary. Finally, it is important to recognize that the causes of hyperkalemia may be additive. Patients may have more than one cause of hyperkalemia at the same time. Therefore, all potential causes of hyperkalemia, including drugs, should be systematically evaluated in every hyperkalemic patient.     

Investigations using a novel monoclonal antibody to the glycosylphosphatidylinositol-anchored protein that carries Gregory, Holley, and Dombrock blood group antigens

BACKGROUND: The high-frequency Hy and Gya antigens have been shown to reside on the same protein. Gy(a-) Hy-negative red cells are also Do(a- b-). A mouse monoclonal antibody, 5B10, was produced with specificity related to the human Gregory, Holley, and Dombrock blood group antigens. STUDY DESIGN AND METHODS: The antibody reacted in direct hemagglutination assays, and its specificity was investigated by radioimmunoassay, inhibition assay, and Western blotting. RESULTS: The 5B10 antibody failed to bind to abnormal paroxysmal nocturnal hemoglobinuria red cells and human erythroleukemia cell line K562, but it was weakly reactive with HEL cells. Red cells, but not other circulating hematopoietic cells, express the 5B10 antigen. The 5B10 antibody had a specificity similar but not identical to that of Gya. Gy(a-) Hy-negative red cells reacted extremely weakly with 5B10 antibody, but Gy(a-) Hy-negative red cells treated with a variety of proteases bound 5B10 antibody strongly. This suggests that these cells express a variant form of the protein recognized by 5B10. CONCLUSION: Identification of a monoclonal antibody to this glycosylphosphatidylinositol-linked protein opens a new avenue for investigation of the biochemistry, genetics, and function of the glycosylphosphatidylinositol-linked protein that bears the Gya, Hy, and Do antigens.     

Transfusion transmission of retroviruses: human T-lymphotropic virus types I and II compared with human immunodeficiency virus type 1

BACKGROUND: The incidence of transfusion transmission of human T- lymphotropic virus type I (HTLV-I) and HTLV type II (HTLV-II) has not been compared directly or to that of human immunodeficiency virus type 1 (HIV-1). The effects of refrigerator storage of the blood component on infectivity of the viruses needs definition. STUDY DESIGN AND METHODS: The circumstances influencing the transmission of HTLV-I, HTLV- II, and HIV-1 via blood of donors whose sera were stored in a repository and who were retrospectively documented as having been infected at blood donation were examined. Confirmation and typing of anti-HTLV positivity in donors and recipients used polymerase chain reaction, supplemented by specific peptide testing. RESULTS: Overall, 27 percent (26/95) of the recipients of blood components from anti-HTLV- I- and -II-positive donors became infected (9 with HTLV-I and 17 with HTLV-II). No recipients of acellular blood components became infected with HTLV-I or -II. There was no probable transmission by components stored > 10 days. The rates of transmission for both viruses were similar: 0 to 5 days' storage, 17 (74%) of 23; 6 to 10 days, 8 (44%) of 18; and 11 to 14, 0 (0%) of 10 (trend, p = 0.0002). In comparison, 89 percent (112/126) of the recipients of anti-HIV-1-positive blood were infected regardless of component type, and no effect on transmission occurred with storage for < 26 days. CONCLUSION: Transfusion- transmitted HTLV-I and -II are similar. The data suggest that a donor's lymphocytes become noninfectious when they lose the ability to be activated or to proliferate.     

Sepsis associated with transfusion of red cells contaminated with Yersinia enterocolitica

Between April 1987 and May 1989, the Centers for Disease Control investigated seven cases of transfusion-associated Yersinia enterocolitica sepsis; four were caused by organisms of serotype O:3, and one each was caused by organisms of serotype O:1,2,3; O:5,27; and O:20. All seven recipients developed septic shock after receiving units of red cells (RBCs) contaminated with Y. enterocolitica; five recipients died. The cases occurred in seven states and were unrelated. There was no evidence for contamination of the RBC units during processing. Six of the seven donors had serologic evidence of recent Y. enterocolitica infection, and it is hypothesized that these donors had asymptomatic bacteremia when they donated the implicated blood. Four of the seven donors reported gastrointestinal illness in the 4 weeks before blood donation, and one donor became ill on the day he donated blood. Y. enterocolitica grows well at 4 degrees C and in the presence of dextrose and iron. If blood is contaminated at the time of collection, storage of the RBCs at 4 degrees C provides an ideal environment for bacterial growth and endotoxin production. These cases demonstrate the need for careful evaluation of patients with transfusion reactions for possible sepsis and suggest a need to screen prospective blood donors for mild gastrointestinal illness, including those illnesses not requiring physician evaluation or medication.     

White cell reduction in platelet concentrates and packed red cells by filtration: a multicenter clinical trial. The Trap Study Group

BACKGROUND: Most previous studies on white cell (WBC) reduction by filtration have been small-scale studies conducted under tightly controlled laboratory conditions. Their results would be the ideal, rather than what might be expected during routine operation. STUDY DESIGN AND METHODS: To obtain information on routine filtration of blood components, data have been collected from a large-scale, ongoing, multicenter clinical trial designed to determine the effectiveness of WBC reduction in or ultraviolet B radiation of platelet concentrates before transfusion in preventing platelet alloimmunization and platelet transfusion refractoriness. The WBC content of blood components both before and after filtration was determined by automated cell counters and a manual propidium iodide-staining method, respectively. Platelet and red cell losses during filtration were measured. RESULTS: The average platelet losses after filtration were 24 +/? 15 percent and 20 +/? 9 percent for apheresis platelets and pooled platelets, respectively. The frequencies at which filtered platelet concentrates contained high levels of residual WBCs (> 5 × 10(6)) were 7 percent and 5 percent for apheresis platelets and pooled platelets, respectively. Further analysis of the platelet filtration data showed that greater numbers of total initial WBCs in the pooled platelets were associated with increased percentages of filtration failure (> 5 × 10(6) residual WBCs). For packed red cells, the average losses during filtration were 23 +/? 4 percent and 15 +/? 3 percent for CPDA-1 units and Adsol units, respectively. The frequencies at which filtered red cells contained > 5 × 10(6) residual WBCs were 2.7 percent for one type of filter and 0.3 percent for another type of filter. CONCLUSION: There were significant losses of platelets during filtration, which could add to the costs of WBC reduction and lead to possible increases in donor exposures. Filtration failures still occurred, despite careful observation of the standard filtration procedures. The number of total WBCs in pooled platelets before filtration has been identified as an important factor in determining the success of WBC reduction.     

MEDICAL PREGNANCY TERMINATION IN THE PRESENCE OF A MASSIVE UTERINE FIBROID

SUMMARY Surgical termination of pregnancy in the presence of uterine fibroids may be technically difficult resulting in reduced efficacy of the termination procedure. We describe the first documented use of RU486 and gemeprost in the successful medical termination of a pregnancy in a uterus grossly enlarged by fibroids.     

Considerations of pool size in the manufacture of plasma derivatives

BACKGROUND: The pooling of human plasma from many donors for the purpose of manufacturing therapeutic proteins increases the risk of exposing recipients of these proteins to pathogens that may contaminate 1 or a few units included in the pool. STUDY DESIGN AND METHODS: This risk is estimated for a range of manufacturing scales that would derive material from a varied number of donors and for a number of hypothetical infectious agents that may exist in the donor population over a wide range of prevalence. Risk is also calculated both for recipients of single doses of a plasma protein and for those who depend on long-term treatment with plasma derivatives. RESULTS: Risk of exposure increases with pool size and the prevalence of the agent in question and accumulates with repeated treatments with material manufactured from different pools. CONCLUSION: Reducing pool size would at best decrease this risk in proportion to the reduction in manufacturing scale. However, for individuals requiring repeated or continuous treatments, the risk of exposure to all but the rarest infectious agents would be only minimally affected, even by large reductions in manufacturing scale.     

Preparation of white cell-reduced platelet concentrates from whole blood during component preparation

This article introduces a new method of component preparation that is capable of producing white cell (WBC)-reduced platelet concentrates (PCs) from whole blood. Whole blood is separated into packed red cells (RBCs) and platelet-rich plasma (PRP) by centrifugation, and the PRP is expressed through a newly designed WBC removal filter into the platelet storage bag. The filtered PRP is then centrifuged and yields WBC-reduced PCs and plasma for freezing as fresh-frozen plasma (FFP). The method uses standard triple-pack blood bags and centrifugation protocols. Fifteen WBC-reduced PCs prepared with this technique had an average volume of 56.7 mL, an average Day 5 platelet content of 8.6 x 10(10) per unit, and an average Day 5 WBC content of 0.83 +/- 0.7 x 10(4) per unit (0.14 WBCs/microL). This represents WBC removal equal to at least 99.9 percent (3 log10) of the WBCs found in standard PCs prepared in our laboratory by an identical centrifugation protocol. Paired studies documented a 4.5-percent platelet loss by filtration. Filtration had no effect on the plasma prepared for FFP as measured by prothrombin time; activated partial thromboplastin time; factors I, V, VIII:C, and VIII:von Willebrand factor; antithrombin-III; albumin; globulin; or total protein. This method holds promise as a simple and highly effective technique for the production of WBC-reduced PCs by filtration during component preparation.